The last few steps along the dusty road were always the easiest… and the hardest.

Easiest, because there was always something comforting about trotting the final few steps home. Hardest, because that meant that the physical toil of farmwork that was every son’s duty was about to begin in earnest… often continuing right to the last gleaming ray of Celestia’s sunlight before it dipped over the western foothills.

The large, jet-black earth pony colt sighed to himself as he reached the gate of Harvest Acres, his family’s farm, inherited through his mother’s side and about as famous and important of an agricultural site as Sweet Apple Acres to the town of Ponyville.

Big Caisson shook his fetlocks clean of the light coating of gravel-dust he’d accumulated along the last half-mile or so of their access road. His mother, Golden Harvest, had been wondering about whether to finally lay paving-stones along the route, not so much for the dust or the look of it, but more to make sure that the wagons wouldn’t get stuck into the ruts that tended to build up, particularly through the rainy weather seasons.

But then he’d gotten his growth spurt.

Mom had quickly changed her mind as to whether he’d have enough power to slog a wagon-train full of produce to market on even the ruttiest of roads. And since there were always a million things to do on a farm, if the family could deprioritize something as laborious as quarrying and laying the thousands of flagstones needed to pave the road, the good ol’-fashioned ponypower solution had quickly won out.

Caisson blew out a frustrated blast of air through his nostrils as he kicked the gate closed behind him, shaking the last of the dust off of his rear-left fetlock as he did so. He hadn’t had the annoyingly hairy fetlocks last season and had begged to go get them trimmed. But his father, Written Script had talked him out of it, assuring him that ‘fillies around this town liked a stallion with big hooves.’

What did he know anyway, as a unicorn he never had to deal with the things! Caisson grumbled internally, shaking his head and heading toward the barn. Fillies had probably flocked all over dad when he was in high school!

In Caisson’s experience, girls had always seemed to prefer the slenderer, sleeker, magic-using unicorns to be their friends through kindergarten, middle-school and right up to the current year. Pretty much every time he saw a magazine in the general store from Manehattan or Las Pegasus, it featured some movie-star stallion that was so scrawny his limbs would break like twigs on the first tug of a single-furrow plow.

Today had been the first day of his final year in high school. His senior year. His last chance to maybe actually bag a fillyfriend before being consigned to the daily work of helping with the farm — after which he’d be consigned to only even have a chance at seeing a member of the fairer sex on market days.

He moaned inwardly as he pushed open the barn door and headed toward his harness-peg, where he’d hung up his gear from the previous day’s work. His one hope was that some of the other stallions would have gone through a similar growth spurt to the one he’d gone through the previous spring, shooting up from lanky coltish-teens to massive young stallions. It had been a crazy few months — he’d always been a bit bigger than his classmates, but for those rainy spring-tillage sessions it had seemed like every day he had to adjust his gear for his increasing size. Breastcollar, belly-band, breeching strap. Each and every session he was having to fish out the leather-punch from the toolbox to accommodate his expanding chest, muscles and bones. It had gotten to a point where Golden Harvest had just kept the punch on a lanyard that she’d hung on the same peg as his gear, to save time for all the constant adjustments it would need.

And he’d had to do most of his work without the use of a good, solid yoke too!

Caisson yearned for the use of a well-fitted yoke... maybe a custom-made one from a skilled craftspony - which would mean shelling out and ordering one from a catalogue. Something shaped out of a solid iron frame, cushioned with quality leather-lining, stuffed with wool. He sighed, remembering the one he’d been able to use when he was younger, a classic piece of gear that he’d shared with his mother as they’d passed each other on the size chart. It was a dream to pull with that thing, so soft and well-worked in, putting all the force right on his shoulders. For years now, he’d had to make do with some jerry-rigged shoulder strap breast collar instead. It chafed way worse and he’d complained, but his mom had simply frowned and shaken her head. There was no way that she was going to spend a few hundred bits on a quality, well-fit, full-collar that he would grow out of in less than a week.

Caisson growled at the memory while walking up to his peg, still devoid of said full-collar.

Though his growth rate had mercifully slowed, Mom would only giggle and hum that he still had a good chunk of growing left. She seemed convinced that he’d taken after his uncle Mammoth’s genes, who was renowned for being unable to get through a doorway even while on all four hooves!

Screw uncle Mammoth and his genes.

He wished he could leave all the giant size, all the big nicknames, and all the growing pains and awkwardness that went with it to rot in the field. It was hard enough to talk with a filly at school when you didn’t look like you were a fully-grown stallion who’d been held back! He preferred when he was called ‘Little Caisson’ as a foal, or at least ‘Caisson’ in middle-school! Now he was saddled forever with ‘Big Caisson’. At least most of his friends and family called him BC for short.

A merciful truncation.

But there had been no mercy from the Goddesses at school today. He’d eagerly looked amongst the various teens of his class-year, hoping to see a few other stallions who’d shot up over the summer break. Surely at least one of them had surpassed him as the biggest stallion? Perhaps one of the members of the hoofball team - they always had so much time to focus on weight-training and workouts after all, not just farming and field-work.

But of course, there had been no such luck for him. Sure, a few colts had sprung up a bit. But if anything, the gap between him and the next biggest senior, a star linebacker, had increased over the hot summer months.

It just wasn’t fair.

Caisson harumphed, then his eyes took in the pile of tackle that was his harness. Of course, he’d left it in a messy tangle at the end of the evening harvesting session the night prior. He always left it in an unsorted pile of straps and buckles. Cursing his past-self, he began to sort through the harness, stealing envious glances at the gear belonging to his two sisters on the other pegs, neatly hanging and awaiting them to return from school.

Just how did these damn straps manage to tangle and bind up just from being dropped on the ground? He groaned internally, trying to trace one of his belly-band straps back to its attachment point. It must be Discord’s magic at work.

He knew he was the only one to blame. It was so easy at the end of a long evening of late-summer work to throw everything off and rush in for a shower, inhale a late supper, then jump into bed – falling asleep mid-jump to eke out every moment of wonderful rest before waking to the cock’s crow the next morning to get a few hours of harvesting in before school. His mother used to scold him for not taking care of his harness, carefully putting everything back in its proper place for him… but as he’d grown older she’d finally decided to leave him on his own and deal with the consequences. Even now she’d still chide him for not taking a little extra time as his younger sisters did.

“Moooooom!?” Caisson bellowed out toward the field as he got the last of his straps out of their dastardly Gordinian knot and began to slip into his harness. He felt the collar-straps slip onto his shoulders, biting into an abrasion that had already begun to form from the previous day’s work. “Can you come cinch me in? I’m about ready to go, now!”

Golden Harvest was always so good at getting everything set just right for him; she’d even spot things like the welt as she strapped him in, adjusting his harness to prevent any such sore spots from turning into permanent strap scars by carefully modifying the seating of the straps or using little pads of wool to provide temporary cushioning.

He grinned at a memory that sprung to his mind, thinking of how adept his mother was at strapping him up. Around the cafeteria table at school, strapping up and whether having a mare or stallion ‘gear-buddy’ was preferable or not had somehow become the topic of conversation. Caisson had quickly proclaimed that his mother was the best in the business at getting him set for a hard day’s work.

That had ruffled some feathers and sparked some horns.

Some of his non-farming buddies at school had reacted with wide-eyed astonishment at hearing that his mother strapped him in. Having your mom so close to your rod and tackle with her snout? Her hooves putting on a crupper dock and having to slide a band along your belly? The questions abounded — ‘Does she ever brush against your sheath?’ ‘Has she ever had to move your sack to set things?’ ‘Does that mean she might accidentally touch your tailhole?’ ‘Dude, have you ever dropped in front of her?’

The answer to all those questions was: yes.

Thankfully, there were enough other farm-colts at the cafeteria table to assist him in providing the eye-rolling responses to the wild imaginations of those towns-colts who had likely never donned a harness in their life.

It was just the way of the world on the farm, things had to get done and that meant hooves and mouths needed to cinch and buckle in places that agriculturally-ignorant ponyfolk might think was more lurid than it really was. He’d never understood what the big deal was anyway, it wasn’t like everypony’s mom hadn’t seen their junk while growing up anyway. He’d never forgotten how a fellow farmhoof classmate had gotten all those tittering spoiled colts to shut up by reminding them all about the first time their mothers had removed their ‘beans’ and taught them to properly wash the inside of their sheaths, their ‘skin-turtlenecks’ in the bath.

That was a task that all mothers did (it would be weird for your dad to do that). After a few moments where every colt around that lunch table had awkwardly remembered their own incidents, everypony’s mouths seemed to shut up.

It just wasn’t that big a deal to have your Mom or your Dad or your buddy strap you up. Every farmpony knew that. Sure, sometimes your little-guy decided to drop-in for a quick appearance, but that didn’t mean anything — just part and parcel of living in a society that had no problem letting it all hang out. Heck, walking around the high school halls in the spring season you’d see more sausage than at the butcher shop the day after the pigs had been taken in.

Hitching up just wasn’t sexual, and that was that. Caisson said as much.

Most of the farm-colts had nodded with him in agreement. Only his friend, Hay Bale, had hesitated at his pronouncement. ‘M-maybe, b-but if a cute filly is getting a little friendly with you while helping you strap up, it certainly could get exciting, kinda?’

Immediately the poor colt had been barraged with questions and excited prodding for him to spill the beans. Everycolt around the table assumed that he’d managed to score with some farm-filly based on his nervous reaction. He’d shaken his head wildly, denying all accusations, just saying that maybe it could be exciting — he wasn’t saying he’d actually gotten to ‘wet his wick’ while slipping into his harness.

With the way his beet-red face shone, nopony believed a word of what he said.

It wasn’t until later that day, on the way home from school that Hay had admitted the truth to Caisson privately. He had made that first perilous leap on the journey to adulthood; his bedpost now had a single notch on it. Although Hay figured that the notch beloned on the inside of his quarter strap instead. Harnessing up with a female-partner had led to a sweaty and confusing tumble in a dark corner of a hayloft.

He refused to tell Caisson just who the filly was, though.

That piqued Caisson’s curiosity. Hay Bale’s family plot was a small one; they had never taken on a farmhand for help, even during bumper-crop seasons. He couldn’t think of any situation in which his friend would have had occasion to get a mare or filly from off-farm to be helping him into a harness, except maybe if he had worn one into town and then taken it off there. That didn’t seem likely though: he was almost never the member of his family who took things to market.

But the alternative was hard to imagine... Hay Bale’s mother had passed away from a particularly horrifying case of Swamp Fever shortly after he was born (she was now a carefully tended tree in their southern field), which left only his older sister as a potential candidate.

Caisson shook one of the loose straps out from under his collar, blowing a snort of air from his nostrils as he briefly returned to the present, before returning to his curious musings.

But doing that? With your sister?

It wasn’t unheard of, especially through the spring seasons in a farming town. Cousins certainly, but even brothers and sisters. He’d heard enough stories, rumors from uncles and aunts visiting during reunions, or from old-timers around Sugarcube Corner when it got busy in the midmorning. ‘No big deal’, they’d say… A mare or filly going in estrus, stallions in rut… scratches needed to be scratched, so long as both parties were careful about protection.

But none of the younger folk he’d hung out with seemed to be OK with the subject, not that it was a common topic of conversation. For his own part, he couldn’t possibly see either of his sisters like… that.

Caisson’s youngest sibling certainly didn’t enter his radar. His baby-sister Posey, hadn’t even gotten her cutie mark yet (Caisson suspected the brat would get a rat-related one for all the snitching she liked to do). She was a complete momma’s foal, and though she could be fun to play with, he always had to be careful not to accidentally step on her (the tips of her ears barely made it to his breastbone height), lest she run off and tell on him to Golden Harvest.

The older of his two siblings, Cookie Pop, was at least within the realm of possibility, being four years the senior of their annoying baby-sister. But she had only just graduated from junior-high: she probably still thought of colts as icky little creatures. That would soon change, Cookie was becoming a looker that would soon turn colts’ and stallions’ heads alike.

Not that he looked at her like that!

Sure, she was a looker. Even as her brother he could admit as much. But that was as far as he would go! He’d gotten the odd glimpse under the tail, of course. It was inevitable, especially around somepony you spent so much time with... the odd swat of a fly of your flank in the field at an inopportune time… heck, sometimes a pony would quickly relieve their bladder mid-pasture row. But to think of those marebits sexually?

He chewed his lip in consternation - that wasn’t right, was it? He was sure most of his friends would frown on the idea.

Perhaps it was a generational thing? Something that made sense in the olden days, but would die out as folk continued to move toward a more modernized future, filled with magic and the industrial advances they all kept hearing about.

Caisson shook his head and grumbled at himself for daydreaming once again.

“Mom?” Caisson bellowed out again toward the field, growing more confused by the moment as to why she hadn’t responded.

Usually, she was pretty timely about meeting up with him to start strapping him in — rain or shine the walk from Ponyville High School was only about fifteen minutes away, unlike the junior schoolhouse, which was on the other side of town. The standard routine was that she’d help him strap up, then his two sisters would help each other when they arrived about twenty minutes later: not a minute to be wasted during the afternoon harvesting season.

The farm always ran like clockwork. He hadn’t seen his sisters harness up in years: usually, he was well into his work by the time they trotted out onto the fields.

“Everything ok, Mom!?” Caisson yelled again, starting to make his way toward the barn door, worrying that something might have happened to her. He always got this sense in his gut before something momentous happened to him, a sort of sixth-sense that some said all earth-ponies had at least some ability to tap into. Was she hurt? What if one of the wagons had tipped over on her!?

“MOM!” He took a stride toward the field, panic rising.

At the same moment, the road-facing barn door creaked open, and his sister Cookie Pop strode in, a look of frustrated annoyance on her face.

“Why are you raising bloody Discord, BC? You know she said she was going to work the south field this afternoon — she can’t hear you.”

“Wha? How did you get here so early?” Caisson asked, arching an eyebrow.

“Early? BC, you dummy… I’m five minutes late because you didn’t stick around to walk back with me after school and I wasted time looking for you!” the taupe filly grumped, puffing out a cheek in frustration.

Caisson could always tell when his little sister was really ticked. The white blaze of fur that ran from her forehead to her muzzle would scrunch up with frustration. But his brain was having trouble catching up — she was looking for him at his school?

Oh.

Oh, horseapples.

“Holy hay, Cookie. I totally forgot that you’re goin’ to the high school now.I-I just fell back into my usual routine.”

“You big dummy.” Cookie harumphed, swishing her brilliant white tail and flicking her nose up in frustration. Her unruly, mane whisked out over her left shoulder as she tried (and failed, seeing as how her head barely met his shoulder) to stare down her nose at him with anger. “How silly do you think I looked on my first day at high school trotting all over the place calling out for my big brother!”

“S-sorry, sis.” Caisson folded his ears back. How had he forgotten that he’d walked to school with her? That Golden Harvest had reminded both of them that they could harness each other up once they’d gotten back home? Had he really gotten that distracted with the first day back?

“Sorry?” Cookie blew a hot blast of air out of her nostrils, clearly still upset. “I bet half the older kids think I’m some crybaby freshman filly now, galloping around searching, yelling out for her big brother to come hold her hoof.”

“N-naw I’m sure-”

A hard stamp of her forehoof against the barn floor cut him off. Her stomps always landed with flashes of white fury - likely because of her noticeable white-fur sock coloration. “It was exactly what I didn’t need after everything else that I’ve been dealing with today. So, y’know, thanks a lot.”

Caisson lowered his head closer to the ground, trying to make himself seem as small as possible. In reality, it barely brought his eyes down to Cookie’s level. He really did feel bad: high school was hard enough as it is — nopony needed to get off to a rough start and score a reputation that could follow her around for years.

“Shoot, Cooks.” Caisson mumbled. “I’m really sorry. I was actually lookin’ forward to walking home with you this year too. Don’t know how I forgot.”

“Hmf.”

“I’m sorry to hear you had a bad first day too…” Caisson lifted his head up, trying to catch his sister’s eye. “Wanna tell me about it while you strap me up? Don’t want Mom and Dad giving us tartarus for falling behind.” He gently rocked his back, making a couple of the tarnished brass buckles clink against each other.

“No.” She grumped, scuffing some loose hay on the barn floor. “Way I figure it, you should be harnessing me first after that stunt you pulled.” The corners of her mouth turned ever-so-slightly upward, from an outright frown to something more of a grimace.

Caisson rolled his eyes and let out a happy little sigh. One thing he liked about Cookie was she never bore any grudges and was pretty down-to-earth and quick to get over little tiffs. Being a little petulant about something as unimportant as who got to harness up first when both of them would end up harnessed was her little way of saying he was out of the hot water he’d landed himself in.

Besides, he preferred being harnessed last. It was always easier to twist down and around another pony to get to the tough to reach buckles without already having your own stuff cinched in.

“You really wanna go first, huh?” Caisson tilted his head and arched an eyebrow high as he shot a friendly grin at her.

“Really.” Cookie managed to hold her hurt expression for a total of five seconds before the beginnings of a smile and a giggle broke out. “You’re such a doof, BC.”

“Fair enough, sis.” Caisson began to shrug off his loose-fitted harness. “Just slip into your belly-band and make sure you cut me some slack, it’s been a long while since I strapped up any mare.” Caisson chuckled, gesturing toward her neatly hanging harness, a fashionable little thing that she’d gotten for her birthday. “Might help if you take a bit of a wide stance so I can figure things out easier.”

A little shiver rippled through Cookie and her posture and expression changed in a way he’d never seen her do before. Was it fear? Embarrassment? He couldn’t tell.

“A-actually,” Cookie mumbled, a blush starting to form on her face as she nervously crossed one forehoof to her other knee and tucked her tail tighter to her, “...maybe I should strap you in first.”

“Oh-kay?” Caisson shrugged, not understanding her sudden reluctance. He straightened himself up, wiggling his body to try to undo some of the harness removal steps he had just begun. “Whatever you want, sis.”

“Y-yeah.” Cookie took an uncertain step forward.

“Been a long time since we hooked up, hasn’t it?” Caisson remarked with a smile.

“Hooked up?” Cookie cooked her head at him, the blush across her muzzle reddening a bit. “BC, what pony ever called harnessing another pony ‘hooking up’?”

“I dunno, we hook-in don’t we? Why couldn’t we be ‘hooking up’?”

“Just shut it, BC.” Cookie groaned, stepping up to his front and reaching out to set his saddle strap. He could barely hear her as she muttered under her breath, “...dummy.”

“I can fix the front stuff sis, don’t worry.” Caisson craned his neck awkwardly to look down at his sister as she reached out and took hold of his left shoulder-strap.

“Yeah, but Mom says you still need help and that I had to keep an eye out for a sore patch on your left.” She reached next to him and grabbed from a small stack of wool pads kept on a nearby barrel. “Don’t want you getting hurt out there.”

“You talked to mom about how to harness me?”

“Sure.” Cookie’s eyes flashed nervously up at him before returning to her work of carefully setting the pad under the strap. “Just… y’know, been a long time since I last got to help you out. I wanted to do a good job.”

Caissan hesitated to reply, raising an eyebrow ever so slightly at his sister’s curious behavior. “Ah, Right...”

“Was almost looking forward to it.” She breathed as much as spoke, before emitting a cough to cover her lapse.

“Yeah.” Caisson replied, examining rafters to avoid staring too much at his sister — who seemed inexplicably shyer than he’d ever remembered her being. “Must be… what, four years since the last time we harnessed each other up?”

“Yeah. Uh, you got a lot more muscle since then,” Cookie grinned, taking the opportunity to trace a hoof down from his withers to his shoulder, along one of the larger cords of muscle fiber that bulged through his dark fur.

W-woah.

The feel of her hoof touching him, sliding down him like that. It made him shiver with sensation.

What was that?

Y-yeah…” Caisson gulped to clear his throat. His mind felt like it needed to reboot - like he’d just caught a blind-side blow from a windlass beam. Why did his sister touching him feel so…

Change the subject, Caisson!

“So! Uh, you said you had a rough day at school. Before my little buck-up, that is. What happened?”

“Ugh.” She tossed her mane again before cinching in his collar an extra notch. “I was the only filly in my class who wasn’t wearing a tail-bun. My friends and I had planned the whole darn summer about how we’d start dressing like real grown-up mares once we were in high school, and of course, I end up catching a late h-” Cookie suddenly cut herself off, standing rigid before biting her lip and continuing, “...of course I end up not being able to wear one.”

Tail-buns.

They were the delight and the bane of every colt in school.

Caisson’s mind quickly flashed through all the ones he’d seen over the last half-year. A filly would fix the bottom of her tail up to her dock with an elastic and then scallop-fold the middle one over another until she met the desired length of her bun, capping her masterpiece off and keeping it all in place with a scrunchie or a bow or a clip. Most of the time the chosen length was little more than a hoof-length.

It left nothing to the imagination.

Of course, the fashion had come in from the big cities, and was quickly derided by many of the older folk as ‘a sign of the moral degradation of Equestrian society’. Just as quickly, as young ponies are wont to do in youthful rebellion, the young fillies in town had flocked to the style.

It was one thing to get a glance of a filly’s private bits when her tail moved, or you were seeing them at a weird angle or whatever. She likely didn’t even know you’d seen anything, let alone meant for you to see her.

But all the time?

And the full thing, too? It was almost as dramatic as some of the pictures he’d seen in Hay Bale’s Playcolt magazines. Not quite a full flag and flash, but nearly as revealing. A pony could see the whole thing at once, even their tailholes - and not even a peek of skin covered by a stray tail hair.

There was something about the fact that the fillies wanted you to see their bits that made everycolt’s heart race.

Add to that the fact his filly classmates were now constantly exposed and it meant that he’d seen some extremely revealing moments. For instance, a girl with a tail-bun couldn’t clamp down (as it could if she was wearing her tail normally) when she had an involuntary flash of pink.

During the school’s health-ed classes, he and his colt-buddies had always laughed at Nurse Redheart when she’d explained that fillies would experience ‘involuntary external genital display’ as often (if not more), than colts. She’d been met with blank stares until she’d gone on to use the laypony’s terms: hard-ons and winking.

The colts had all scoffed and balked at the assertion. One had even muttered ‘horseapples’ loud enough to catch a stern look from Principal Cheerilee, you only had to take a stroll through the hallways at lunch to see at least a half-dozen colts awkwardly bending their knees, hoping to lower their barrels enough to conceal that they were rigid against their bellies. Two-dozen if you went around counting stallions who had only dropped (but everypony knew that didn’t count).

But the fillies in class had unanimously agreed, protesting against the boys’ doubt. ‘Just because you don’t have Supermare x-ray vision to see through our tails doesn’t mean it ain’t happenin’ fellas.’ Still, despite their protests and Redheart’s confirmation, everycolt had remained skeptical.

Until tail-buns.

Putting aside whether or not Caisson thought seeing a mare’s bits was arousing, seeing a filly’s lips tense, pull up and part — before flashing a bulging pink nub of a beacon out, along with a hint of her velvet depths was hot. The tail-bun trend had only been around for the last two months of his junior year, but he’d ended up seeing nearly every one of his class-fillies’ buttons at one point or another. He’d never thought they could vary so much in shape and size — though he supposed it made sense considering their homolog did as well.

Nearly every time he walked down the hall, he’d catch at least one pink-blip out of the corner of his eye, though the filly in question would quickly look away from him with an embarrassed blush when he tried to meet her eye.

Caisson always figured they were probably looking to hook one of the smaller, slenderer colts.

The ideal filly-form had been the prime source of conversation around the colts’ cafeteria table for weeks at the end of the last school year, every lunch they’d compared differences between their classmates of the fairer sex in great detail. Generally, discussion stuck to the external bits though: it was a rare session when another farmcolt would describe what one of the filly’s hidden-pearls looked like, though most of the other colts would thump him on the back and congratulate him for doing so. Whenever that happened, Caisson would glance over at the smaller, slender, fashionable ‘popular’ colts at the table — they always seemed to keep silent about the gallery of flashes they were surely receiving: so he would too.

But despite their excitement and delight, it was also the bane of colts at Ponyville High.

Erections.

Erections for miles. As far as the eye could see.

Completely unavoidable.

There wasn’t a colt in school that Caisson hadn’t seen every inch of. And, of course, he was sure the fillies’ table at the cafeteria had its own contrasting and comparing discussions.

It was particularly bad for Caisson - thanks to his bulk, the tried-and-true method of crouching in the knees to at least drop out of an easy sight-line was completely useless. Hay, some of the smaller fillies were basically eye-level with his underbelly! He’d gotten through the remainder of the semester by always staying seated, or laying at rest - keeping himself hidden under a table, behind his forelegs or under his barrel. If he was moving from class to class or along those pink-flash-minefield hallways, he’d quickly break into a trot or even a gallop if he felt himself drop.

He’d nearly made it through to the summer break as the school’s last ‘undisclosed’ colt, until the incident.

Remembering that made Caisson wobble on his hooves.

“Did I strap it too tight?” Cookie’s concerned voice snapped his ears forward. She’d paused just as she was finishing up his forward harness. “Is it cutting into that sore spot? Mom said to use the fourth belt-hole; should I put it in the fifth?”

“N-no, that’s fine, it’s not that.” Sheesh, why am I so spacey today? He brought his eyes back down to his little sister and smiled. “That’s weird about not being able to wear a bun though — didn’t think Mom really cared about the fashion. At least, she always seemed to poke fun at the old-timers who were getting so screwed-tight about it.”

“She doesn’t care about the tail-bun. She’s fine with me wearing one.” Cookie grunted, tying off the remaining working-ends of the now buckled collar-straps into neat belt-hitches so they wouldn’t bounce around annoyingly. “She won’t let Posey wear one, obviously, but now that I’m in high school I’m allowed.”

“Oh. So why didn’t you?”

Cookie took a step back from him again, that weird look of embarrassment washing over her and her un-bunned tail tucking tight against her rump again. Embarrassment quickly gave way to an indignant set of sharp eyes.

“That’s — that’s none of your business!” She snapped, ears folding against her head.

“Wha? S-sorry.” Caisson shrugged. He’d never understand mares.

“Dummy.”

“Anyway, sorry your first day was so crummy.” Caisson rolled his shoulders, judging how well his sister had attached the collar and shoulder straps. Everything moved like a second skin on his body: not chafing or rubbing, snug but not tight, supportive but not restrictive. She’d done a good job.

“It wasn’t all bad.” Cookie admitted, nodding at her own hoofiwork, impressed with how she’d gotten things in place. She moved toward Caisson’s rump. “I got to learn some new things about my famous big brother for instance.”

Caisson stiffened. Did she find out about that incident?

“Rear-harness now? Or middle?” Cookie asked, already making her way to his tail.

“Uh, rear.” Caisson liked his belly-band to be as comfortable as possible - he always found that having a snug fit in-front and in-behind it before snugging it down to help with that.

“Mhm.”

As she turned, Cookie’s tail brushed against his left shoulder. There was something lingering in the air behind her. A hint of something he couldn’t quite place - cinnamon? Cookie wasn’t one to wear perfume, though. The smell lodged in his nostrils and to the back of his throat like a sticky mist; everywhere it touched seemed to grow hot and tickly inside his mouth and nose. He scrunched his nose up and opened his jaws as he lifted his head toward the ceiling involuntarily to attempt to clear the cloying scent.

What was that?

“H-hey!” Cookie chirped, tapping him on the flank and making his head snap back to attention. “Ready?”

“Yup.”

“Spread ‘em out a bit so I can see better, never harnessed a stallion before.”

“You strapped me up back in the day.” Caisson reminded her.

“You were more of a... colt back then.”

“You never helped Dad out?”

Cookie shook her head. “Naw, you know most of the time he’s on magic duty. And whenever he does need to pull something he’s pretty fussy that only Mom set his straps.” She clicked her tongue then shot Caisson a pointed glare. “Now quit stalling and let me see what I’m working with, BC.”

Caisson blushed a bit, despite himself. Why does this feel so weird? Why is my heart racing? Slowly, he stepped his rear legs about two hooflengths wider than his resting stance, as if he were digging in before trying to yank a stump out. She’s seen me a hundred times since I’ve had my growth spurt, how is this any different?

But it was different. Whether it was that smell in the air, the tight proximity of the two, or the way Cookie’s eyes seemed so intently focused on his butt… this was exciting.

“Tail too.” Cookie complained. “Sheesh, you’re acting like a blushing bridesmare.” But Caisson could see the intensity in her eyes — did she want to see?

He lifted his pewter-gray tail and moved it to one side, further than he even needed to - enough to even show his tailhole. There was nothing between his rump and his sister’s eyes now.

He watched as Cookie’s eyes flashed wider, more than a casual reaction. The blush on her face seemed to flush all the way to her eartips. The filly’s mouth fell open slightly for a half moment and Caisson swore he started to see his sister’s white tail start to rise above her rump.

Then she suddenly slammed her rear down against the barn floor into a sitting position, hiding it from view.

All he could see was her make the strangest wince for a moment, one eye contracting slightly as she bit down on her lip — as if somepony were plucking a splinter from her frog. He could see the end of her tailhairs behind her as they swished on the barn floor once or twice, then the moment passed.

“You OK? W-what was that?” Caisson asked, tilting his head.

“N-noth- *ahem*” Cookie’s voice had first come out as a croak, necessitating her to awkwardly clear her throat and thump her chest with a forehoof. “N-nothing.” She folded her ears backward against her skull. “Just a cramp.”

“You sure?”

“Yeah, BC.” Cookie swallowed again. “Just give me a second.”

Caisson watched as his sister did the weirdest little shuffle, wiggling her butt against the wooden floor of the barn a few times in a way that reminded him of when the family collie had an itchy backside.

“W-what?” Cookie shot at him, unable to meet his eye.

“Nothing.”

“Ahem.” She cleared her voice again, patting her breast then let out a steadying breath and stood back to all fours.

Caisson’s nostrils flared as she rose. Whatever that hint of a smell had been before, it was filling the barn now. Every breath he took was heavy with that strange cinnamon musk, hanging thick in the warm air. Not that he disliked it — with each breath he would swallow, as if he could actually drink any of the mysterious perfume that had condensed in his muzzle.

He felt something in his gut twitch, a little shiver that roiled into his groin. He quickly gritted his teeth, and tensed his abdomen. He had a sneaking suspicion if he didn’t clench up a bit he might drop right then and there.

“You, uh, certainly got bigger since the last time I saw you.” Cookie interrupted him, flicking her eyes up at him as he looked over his shoulder at her. Caisson saw her ears slowly tilting back up with growing confidence before she cracked a grin. “I remember ‘em being a lot smaller.”

She’s talking about your sack!

“H-hey now, ain’t nice to tell somepony they’re packing on pounds in the rear.” Caisson nervously joked, trying to pretend she was talking about something else.

“Pft.” Cookie scoffed, stepping up as her grin became sharper - her muzzle was almost level with the organs in question. “Last time I got a look at ‘em they were like a pair of acorns, but now these are more like a couple of buckballs in a leather pouch.”

As she said these, Cookie’s left hoof reached under and lifted his right testicle, as though it were the most natural thing in the world. Caisson’s heart skipped a beat, a surge of adrenaline and excitement pouring through him as he felt his sister’s soft frog, her delicate underhoof, press against the slick skin, hefting him and feeling his weight.

“...heavier than one of ‘em though.”

She’s touching me… down there! Caisson’s mind popped with shock. He wasn’t sure why he was getting so excited by this, he knew that lots of touching could happen when somepony was harnessing up. But even his mom hadn’t just… fondled him like that!

“Don’t they bug you? Bouncing around against your leg?” Cookie asked, even as she moved his sack carefully up and to the right, slipping a quarter-strap along the inside of Caisson’s left inner thigh. The thinner, lighter straps were used to keep the larger britchen strap that ran across his buttocks in place — especially with a temporary harness like Caisson’s, these were needed to keep the critical larger strap from sliding up and down.

But they certainly ran right extremely close to some very fragile equipment.

Colts nicknamed them ‘gelding-straps’ for a reason: if you got a bit of your junk pinched when hauling in to tighten up the britchen… a common joke was that the Canterlot opera could always use more male altos. Still, the amount of movement and holding that his little sister was doing to take care and give proper clearance seemed excessive.

“Uh… I… not really. As much as any stallion I suppose.” Beads of sweat were popping out on his forehead - he couldn’t clench much longer.

“But yours are so much… bigger.” Cookie squeaked, as she shifted her hoof across the underside of his pouch, carefully taking hold of his right orb and moving it out of the way of the right breeching strap.

“Really? Hadn’t noticed.”

“Sure - Dad’s not this big.” Cookie remarked. “The mares around town say you’re even bigger than Big Mac in his prime.”

“They talk about my… uh… tackle?” Caisson hesitated to use other terms with his little sister, hoping to preserve her innocence. It was hard to reconcile that innate desire to be a protective big brother at the same moment she was groping the tackle in question, while informing him it was apparently a source of town gossip.

“Your balls?” Cookie giggled. “Sure, though I gotta say, up close they’re even more impressive than I’d heard.”

“C-cookie…?”

“Sorry, sorry.” Cookie quickly interjected before he could scold her. She held up a hoof by way of apology, letting his dangly bits come carefully to rest in their black smooth-skinned coin-purse. “I ramble a bit when I get nervous.”

Caisson let out a little breath, finally able to release a bit of the clenching tension he’d been using to suppress dropping. “Why are you nervous.”

“N-nervous?” Cookie blushed, her ears folding back. “I… I’m not nervous.”

“Then why did y-”

“Anyway, crupper’s next.” Cookie hustled quickly, avoiding his question.

She was pretty nimble at threading his tail through the crupper-loop and drawing it up under his dock. The leather-covered loop slid up his taint, bumping over his tailhole and then settling comfortably against the notch of his dock. Caisson shivered when the loop touched his backdoor: he was always a little nervous about it, and showing such a private area certainly didn’t make him any more comfortab—

“Boop!” Cookie’s hoof poked him right in the middle of his pucker.

“Gah!” Caisson barely suppressed the urge to instinctively kick backward, but he couldn’t help but stand stock straight, a shiver rippling through him. This also had the effect of getting him to release his spartan-like tensing of his lower abdominal muscles.

He felt himself start to slip from his sheath, the flesh pouring out from inside him like some sort of meat-slinky. It was impossible to stop dropping once it had started, only slow it down. His only saving grace was that Cookie couldn’t see it from her angle.

Yet.

With the bellyband still to go, avoiding giving his little sis a face-full of ‘little Caisson’ was no longer an option. He only had one hope now.

Don’t get hard. Don’t get hard!

“H-hey!” Caisson choked out, as soon as his mind had set on the new gameplan. “What’s the big idea!? I nearly kicked the teeth outta your head, Cookie!”

“Pft, hahaha!” Cookie laughed mirthfully. “Sorry BC, couldn’t help it. Mom said you were touchy about your butthole, I had to pay you back for all the teasing you’ve given me over the years.” She stuck her tongue out at him playfully, without any of the malice of a real tongue-out rebuke.

“Yeah, well… let’s see how you like it if I poke your tailhole when I’ m strapping you in!” Caisson harumphed, grumpy that a stupid prank had ended up overcoming his efforts to keep himself tucked-up.

“Pft, I don’t care.” Cookie waggled her head tauntingly. “I ain’t a delicate flower like you. Won’t bother me if you prod my ponut.”

The words took a moment to process in his mind, but when they did — a flush of red crept over his face and his eyes bulged.

Cookie noticed, her blush deepening as well.

“N-not like that!” She shouted immediately. “That’s gross!”

“I didn’t say anyth-”

“I ain’t that kind of filly! You’ve been spending way too much time with those depraved city-colts!”

Caisson had heard rumors from several farmers of both sexes which disproved that the orifice in question was only the fantasy domain of depraved city-colts. But this was not the time to bring up those rumors. How did I get into this situation with my sis, anyhow?

“I’d never imply tha —”

“Just drop it BC,” Cookie harumphed. “You better not poke me there, dummy.”

Caisson just vigorously shook his head in agreement, keeping his mouth shut.

“Ok then.” She sighed, stepping back and nodding. “I’ll tighten your breech straps then— ah.”

Ah.

She was standing stock still, on his left side. Her big blue eyes wide and locked on… him.

He wasn’t completely dropped out of his sheath yet, but there was no way what was out could escape notice. And she’d never seen him like this: there was a difference between a ‘little’ drop like a colt might do to take a leak — something she’d probably caught the odd glimpse of here or there.

But this was one of those drops that happened before springing into a rock-hard stiffy, where a stallion’s body would completely relax and let every bit of phallic flesh hang-out for all to see.

Inches upon inches of pink Caisson meat arched droopingly toward the barn floor. The damn thing might already have been touching the ground if it didn’t have just enough blood pressure in it to give it a lazy, floppy curve as it extended further.

“Ah.” Cookie repeated. The curt phrase made Caisson think that maybe she was stunned into a brain-reboot of her own.

“S-sorry.” Caisson apologised.

“O-oh?” Cookie tilted her head, turning back to him then shooting a very nervous smile. “Oh! Oh don’t. Don’t apologise.” She laughed, not the mirthful giggle of earlier, but a nervous chuckle to conceal fear and embarrassment. “It… it’s normal, you know. Dropping.”

“Y-yeah.”

“Mom said it happens.” Cookie rambled quickly, words tumbling out one after another. “Just means you’re relaxed is all. Means I’m doing a good job and you’re comfortable letting your muscles unwind.”

“Y-ye—”

“Doesn’t mean that you’re doing it on purpose. Or that it is for sex. L-like an erection, I mean. Could just be you’re mellow and calm.” Cookie’s words seemed to be going even faster as she went along, her eyes nervously darting between Caisson’s face, then back under his belly. “Mom said that, if it happened, just ‘cuz it’s out doesn’t mean that you’re getting a hard-on for me.”

“N-n—”

“Not that I’m saying I’d be angry if it was. Um, a hard-on. For me, I mean.” She was completely stream of consciousness now, words bumbling out of her lips in fumbling futility, her embarrassment growing moment after moment. “Mom said it isn’t a big deal even if it was. Just a compliment. A nice compliment for a filly, is all.”

“C-cookie, I—”

“So, thanks for the compliment! If it is one, I guess. Don’t mean to imply. Compliments are nice. It’s nice. I should give you one too; that’s what Mom said. ‘Stallions are proud about their penises!’

“I—”

“Not that I’d give you a fake compliment! Y-your stallionhood is nice! Real nice.” If her face turned any redder she’d put make Big Mac himself look blue-furred by comparison. “I mean it’s big. Real big. Huge. Really impressive, BC — you should be proud! And you aren’t even hard. Are you? Are you getting hard?”

Finally, the non-stop stream of consciousness babbling ceased, and Cookie clammed up, her face scrunching into a cute, derpy expression before she groaned and slapped her hoof to her face, hanging her head.

“C-cookie.” Caisson finally finished a word. “S-sorry—”

“Don’t.” Cookie sighed, still hiding behind her hoof. “I told you I rambled when I got nervous. Here I am, acting like a tittering school-filly and sticking my hoof in my muzzle.” She groaned. “You must think I’m as silly as a foal.”

“No, not at all.”

“Ahem.” Cookie cleared her throat, letting out a little breath before holding her head back up again. “Let’s just go back a minute before I babbled on like a librarian with a parasprite infestation.”

“S-sure.” Caisson nodded letting out a sigh of relief.

There was such tension in the air, an inescapable energy that he had just never felt before — especially around his sister. Just this morning he had sat across from his little sister at their breakfast table, happily gulping down oats and only half-listening to her chirping about how excited she was to start at her new school. She was just his little sister after all.

But now…

It was like he was realizing for the first time that she was a filly. A mare even. The way she looked, the way she looked at him — even the way she smelled. There were two versions of Cookie in his mind — the one that he had taught to throw a buckball, the one that he had taught how to climb a tree: his cute little sister. The other version was the one he was just meeting now: a female that was not only interested in him — but also was dripping with sexiness.

Her beautiful face, her twinkling eyes, wild mane… lithe body and pert little athletic butt: it made his heart thump.

Caisson didn’t want to admit it to himself, but he kinda, sorta, maybe just a little bit… wanted to get a good look under her tail.

And that scared him — almost as much as it excited him.

“I’ll tighten your breech straps now.” Cookie said, affecting a professional demeanor. She glanced down at him, as if noticing for the first time “Ah, that’s a very nice penis BC.” The way she said it was as if she were grading a pumpkin at the county fair.

“Th-thanks?” He tried to hold back his laughter at her little act, almost made it too. But soon the chuckle escaped.

“Hey! Quit it!” Cookie growled at him, shaking a hoof menacingly. But shortly she was giggling too.

She rolled her eyes resignedly, before going back to work. Quickly, Cookie reached under him with her muzzle, getting her teeth close to the smaller buckles that rested along his inner-thigh.

Caisson stopped chuckling.

He could feel her breath along his lower belly now, warm puffs of air from her nostrils washing right over the base of his sheath, over his sack.

She’s certainly taking her time getting that strap settled — and did she really need to do it with her muzzle? She could have done it with her hoof, instead.

“Got it.” Cookie hummed. “You uh, smell really nice, BC. Just saying.” Her tail flicked out in a lazy whip.

“Th-thanks.” Caisson automatically replied. He wasn’t sure how a faceful of stallion-junk could smell nice though, it wasn’t like he had applied any deodorant down there, let alone one of mom’s perfumes or scented oils after his morning shower.

“Other side, now.” Cookie explained, her tail flicking again.

Caisson nodded, expecting her to remove her head from under his belly to walkaround him and lean in from the other side. He was caught off guard once again when instead the filly stepped further under his body, sliding her muzzle over toward the other thigh.

Of course, this meant that she was practically nuzzling the base of his stallionhood. The thick base where his organ met his belly now rested right across his little sister’s nose, draping the rest of his semi-flaccid stallionhood over her left ear and along her neck, the sensitive end of his pride bumping along her barrel.

“Mmmf!” Caisson moaned, unable to bite his lip shut in time. He had never imagined when he’d woken up that morning that he might end up laying pipe right across his little sister’s face.

He was intensely aware of every little movement as she fiddled with the buckle and strap, each shift of her head causing him to bounce and slide along the soft, short fur of her nose and face.

“Mfhthere.” A muffled confirmation of success came from between his legs.

But she didn’t pull right out from under him, instead turning her head underneath his junk as if the fact she was blinded by his stallionhood had caused her to get lost beneath him. She slid her nose more toward his rear end as she stepped even further underneath him, finally bringing his drooping mammoth of a dropped sausage right down the middle of her muzzle — the slowly stiffening tip of his stallionhood resting at the nape of her neck between her shoulderblades, like some obscene pink pool-noodle had been flopped onto the filly’s face, neck, and back.

She stepped forward, bringing her muzzle right underneath his balls. As she lifted up, her nose firmly embedded in the folds of leather-like skin, each of his pendulous orbs slid to one side of her muzzle.

And then he felt something, something wet.

He couldn’t tell if it was a lick, or perhaps the end of her wet nostrils flaring and snuffling, but it came with a heavy heave of Cookie’s barrel as she took in a deep inhale of his musty sack.

“Mmnghuck…” A strange moan came from beneath him, his sister’s cry drowned out in the dark flesh of his scrotum. He felt her tail brush up underneath him, ticking his ribcage as it lashed left and right wildly.

*Splat!*

A wet, pitter-spatter sound made his ears flick; somewhere under his body a half-cup of liquid had splashed against the ground.

That cinnamon scent became a fog. He could almost feel the humid heat of the pheromone-laden musk warming his body as the aerosol raced into his sinuses. His nostrils flared wide, heaving in air to gulp down the raw, sexual perfume... And everywhere the erotically infused oxygen raced through his blood stream he began to heat up, his huge heart pounded faster than when he’d run the quarter mile race at school, his muscles stiffened and throbbed, his hairs stood on end, his arteries and vessels expanded — as a wave of testosterone slid from his head to his hooves.

A wave that went right into his stallionhood.

A heavy pulse of red-hot stallion blood gushed into his groin, fattening the pink cylinder of flesh laying along his sister’s back with shocking speed. And each pulse was followed by another, the muscles of Caisson’s abdomen now letting a cascade of boiling, inflating blood gush into his massive stallionhood, lifting the huge beast of a penis as his heart pumped madly.

Inch after inch, his cock grew, sliding down his little sister’s spine, the bulging head bumping along each vertebra before the hydraulic pressure of his erection finally began to lift the mammoth thing off her body, slowly raising it with each thump of his heart up to his belly, as slowly as a drawbridge lifting to permit a ship to pass under it.

And each beat grew his erection too, transforming the already impressively large form of the once drooping slinky. His shaft fattened, thickening to a girthy, vascular log. His head expanded, growing wider and wider until finally, he felt the familiar touch of himself against a spot on his chest, just below his breastbone.

He had a boner.

“Ah, sorry about that.” Cookie’s voice floated up to him, as she began to extract herself from underneath him. Her tail swished left and right, its wild ends tickling his pink tip as her muzzle and head carefully extracted itself from underneath his body — leaving one last semi-nuzzle against his swollen base. “Got a little lost under th-”Cookie paused, taking in what Caisson assumed must have been a perfect side-on view of his shame.

“H-holy buck.” Cookie let out a breath, eyes wide in shock. “So that’s why they call you BPC.”

Oh crap. Caisson’s stomach dropped. She had heard about the incident.

It had been late in the previous school year: that magical time when all the exams were finished, when the hot early-summer afternoons beckoned, when teachers had little teaching left in them, and were more about excited gossiping and planning for the upcoming holiday months.

Like the other colts at Ponyville High, Caisson had managed to endure the beginning of estrus only through sheer willpower, stoic resolve, and a reliance on his good upbringing. Thankfully, most of the fillies tended to go into their cycle around the same time, whether by some magical influence from the Princess of Love (as some devotees of the princess of the Crystal Empire claimed) or the more likely reason that females of any species tended to synch up when grouped together over time.

In any case, there were always two or three weeks a year where fillies would suddenly start smelling a whole lot more interesting. And that wasn’t all: they were more fun too! Fillies would become less shy about coming up and talking to him, laughing at his jokes and pawing at him, giving little hugs in the hallway, and getting a lot more touchy-feely. They looked amazing too — it seemed like they positively glowed.

But, filly by filly, they would get taken aside by Cheerilee and told to go home for the day — and that they weren’t expected back at school for at least a week. At times Caisson felt like the pink-maned teacher followed him through the halls, sweeping up any filly that came too close to him.

He was sure that she did it for the other colts too.

Not that it was a fun holiday for the fillies: they still had to do all of their homework, often being homeschooled by one of their parents or teachers that would make the rounds. And all that was in addition to enduring the powerful physical symptoms of estrus: sweats, hormones, emotions, cramps, desires.

Sure, some fillies would take that ‘moon-tea’ stuff, that was supposed to make things more bearable for them. They covered the potion in health class, a natural suppressant that prevented the worst effects of estrus, including pregnancy. When they did, half the fillies in class would roll their eyes at the mention of the ancient solution, listening to their complaints it seemed about as effective as throwing a teaspoon of water on a barn-fire. Ponyville was also an old-school farming town. Most of the grown-ups and elders still saw moon-tea as more useless than a chocolate horseshoe — in their minds the whole point of buckin’ was to get plenty of healthy young ponies who could help out with the farmwork. The act without foals was just — wasteful.

So aside from the odd filly that was blessed with a less serious cycle, for a couple of weeks each year Ponyville High would become an all-boys school.

This, too, was for the best. As aggressive as fillies during heat-month could be, it was nothing compared to a stallion going into rut.

Every son had been warned by their father about the signs. Snorting, stamping, feeling restless, dropping every other minute… generally feeling like you were able to get any mare you set your eyes on. Every colt was taught from a young age to quickly remove themselves from whatever situation they were in at the earliest signs — getting to a cold shower and fresh air as soon as possible.

It was not an acceptable excuse to chalk up bad behavior as ‘just going into rut’ or ‘colts being colts’. Those days were left in Equestria’s history. Colts had to be responsible for their bodily functions just as much as fillies did — and that meant watching for the signs.0

And they were watched closely too, by all the adults in town.

A wild stallion or colt going into rut was not a fun time.

But with the precautions of removing fillies from school, and the grown-ups mostly shacking up with one another, it had been many seasons since the last instance of a wild, public rutting… though ponies still joked about how Uncle Carrot Cake’s all natural frosting had coated half the town fountain… as well as Aunt Cup Cake.

So it was that every colt that aspired to be a gentlestallion knew that you didn’t go after a filly during those estrus weeks. There was the danger of going into rut, and it was somewhat unsporting: ‘If a filly doesn’t like you when she’s off her hormones, she really won’t like you if you take advantage of her when she’s on ‘em’.

And Caisson had been raised right.

So he’d waited until peak heat had died down, trapped in a school filled with other colts, all of them spending every free moment egging each other on to take a shot at asking out their dream-filly once heat week was over — though it wasn’t quite sporting to go after a filly when she was on her heat, that gray zone just when she got back from the mandatory homeschooling and was still somewhat receptive was considered fair game.

And Caisson had set his target high.

A cute earth-pony by the name of Cutie Hoop — a popular filly in the class who was known to be a studious reader academically, often to be found buried in some giant book behind thick-rimmed glasses… until she went to the buckball field, that was.

There she would transform into the star cheerleader of Ponyville, with moves and grace that made pegasi swear she was part pegasus, and a magnetic glow that made unicorn onlookers think she must have magic-pony blood in her veins.

To Caisson, she might have well as been an alicorn princess.

So it was that, on her first day back, with nary a few weeks left in the school year, Caisson had felt his oats and made the decision to walk up to her in the cafeteria during lunch hour and ask her if he could come watch her at her practices after school.

Never mind that he couldn’t spend more than five minutes after the final bell rang before needing to sprint back to the family farm. Or that he had no idea how asking to ogle her from the sidelines would get him any closer to a date with her. Or that he was a complete, bumbling buffoon of a colt when it came to talking to girls.

It really must have been the lingering effects of estrus in the air that got him to stand up and take those nervous steps toward her table that lunch hour. Maybe he really was in the early stages of a rut to think he had any business making such an attempt — the fact that his stallionhood was stiffly bobbing against his underbelly certainly gave some credence to that possibility.

But he’d shuffled carefully, keeping his heavy organ out of sight as he trotted up to Cutie Hoop’s table.

Instantly, all the fillies had stopped their conversation and looked over at him, eager grins on their faces and welcoming smiles — which nonetheless made Caisson feel like he was under a spotlight of pure female focus.

His words began to stumble and stammer out of his mouth; what was he even saying? He wasn’t sure, not in the moment nor thinking back on it now. All he remembered was that Cutie’s face had started to beam with joy; he was saying something right.

And that’s when it happened.

He’d never found out just who it was, and whether it was on accident or intentional, but a pony passing behind him had bumped against his back leg.

In his heightened state of awareness and agitation, his body already flooded with adrenaline and wired to a hair-trigger for reaction his nerves fired long before his brain had any chance to decipher the innocuous sensation and interrupt his startle reflex.

Millions of years of evolution made him rear up in fright, with a tremendous whinny that cut off whatever bumbling question he had been asking to the lunch-table fully seated with cheerleaders.

Normally, this wouldn’t have been so bad — everypony might have an unexpected rear or buck if something surprised them, and quickly shooting your forehooves up onto a table like this startle was about to make him do would be cause for little more than a giggle… but Caisson had a very long, thick, heavy, organic lever attached to his body.

And the laws of physics are cruel, unforgiving mistresses.

He could only imagine what it must have looked like to half the cheerleading squad as he reared up — the swinging arc of his huge, pink stallionhood along with his swinging sack must have been quite the sight. He still remembered the heavy slap of his rigidness against his belly as he reached the top of his standing rear. His forehooves came back down hard onto the cafeteria table, making two solid *clunks* that filled the air of the cafeteria.

But an object in motion will tend to stay in motion, until another force or object opposes it.

And the hanging log of flesh under his barrel continued swinging downward even after he arrested the fall of his chest… until it was opposed by the table.

*KA-SWAP*

The sound still echoed in his ears, even today — the fall of his goliath stallionhood landing with an equal-parts heavy and wet slap on the fillies table.

The impact sent every tray on the tabletop to clattering, launching the wet mash of peas most of the girls had selected as their sides into their well-coiffed cheerleader manes and faces… and splattering back over his shaft.

For a moment, there was no movement, no noise. Every eye in the cafeteria was drawn to the table and the sound — where it looked bizarrely like the centerpiece to the cheer-squad’s table was Caisson’s heretofore unseen, nineteen-inch, bright-pink, thick-as-your-hoof, horsecock.

Then the moment passed.

Shrieks and shouts came from everywhere.

“Holy buck!”

“Lookitthesizeofthatthing!”

“I knew it!”

“...ould kill a mare with tha-”

“...never fit into-”

“Freakishly huge!”

“Damn BC!”

Somehow, the din had dipped just enough for every pony to hear Cutie Hoop as she carefully worked her hanging-jaw closed, wiped the mashed-peas off her glasses and stated with awe:

“That is one BIG… PINK… COCK!”

Caisson was in complete fight or flight mode by that point — he’d started screaming apologies, righting himself and dismounting the table, ears folding back and tail tucking under himself as he continued to bark apologies in every direction. He wasn’t sure if the echoes in his ears were all the ponies picking up Cutie’s apt description… or just his mind letting the reverberations of the most popular filly in school bounce around in his skull like the ripples from a boulder thrown into a still pond.

“BIG… PINK… COCK!” “BIG… PINK… COCK!” “BIG… PINK… COCK!”

He galloped.

Out of the cafeteria. Out of the school. Out through the field. All the way back to the farm.

Where he hid in the barn until it was time for chores — he’d never skipped class before, but it had seemed like a pretty darn good time to start.

Of course, he couldn’t skip school for the rest of his life, as much as he wanted to. Golden Harvest had nipped at his flank the next morning when he’d tried to pretend like he’d caught a summer-flu: she didn’t raise malingerers, and had a keen eye for when her kids were actually sick, like any good mother.

That next morning, slinking in through the back-forest paths to school, and trying to slip into the back of the gymnasium for morning assembly,Caisson had nevertheless received a standing ovation from the entire student body.

Of course it had been organized by the colts — Hay Stack had jumped out in front of the students seated in the bleachers as soon as they’d spotted him walk in the door then announced loudly to everypony present:

“Here he is folks! The prodigiously penis-endowed pride of Ponyville High… our part-elephant, part-blue whale stud… our five-legged farmstallion… BC - no…” He stopped himself, then turned dramatically to the crowd.

“... BPC!!!”

All the students (and even some of the faculty) began stomping their hooves, a stampede accompanied by a cacophony of cheers and whooping (mostly from the colts), and giggles and whispers (from the fillies).

“AHEM.” The purposefully loud feedback of the screeching microphone from Principal Cheerilee ceased the crowd. “I’m glad everypony is so proud of Caisson, but that’s quite enough… Hay Stack, I think you’ll benefit from a week of detention for this little stunt.”

“Worth it!” Hay Stack yelped, pumping his hoof and receiving a number of back-slaps from the colts.

“Two weeks.” Cheerilee quickly added, silencing him. “As for the rest of you, I know this is all good-natured cheering, but I had better not hear of any of this going too far or teasing one of your fellow students. Everypony’s bodies are different: size, shape, color, race or species are not the basis of our judgments. In Ponyville, we judge only the content of one’s character... and their baking skills!”

That got most of the students quiet and pensive.

“However,” Cheerilee’s eyes focused in on Caisson at the back of the gymnasium, “I don’t believe that I’ve ever heard of a pony’s… blessing being used as an excuse to cut class. Regardless of how large it was. Big Mac certainly never skipped any classes.”

“Big Mac has got nothing on BPC!” Hay Stack chirped, causing another round of raucous cheering.

“Three weeks,” Cheerilee growled, leaning into the microphone then sighing. “Well, Caisson, your friend has just taken the week of detention I was going to give to you, so I guess you can thank him… and if we can get back to our announcements…”

“You know about that?”

“BPC, everypony at school knows about that,” Cookie smirked — her eyes pulling off of her big brother’s tool with reticence. “It was like I was a minor celebrity today — every filly asking me if I was really the sister of the BPC.”

Caisson groaned, one of his forehooves coming up to massage his head. “Great, so now my little sister knows I’m the laughingstock of the of the whole school.”

“Laughingstock?” Cookie incredulously clicked her tongue and raised an eyebrow. “You kidding me? Try hero-hearthrob.”

“What?”

“Every filly from every grade was chatting me up all day today!” Cookie grinned, her tail flicking back and forth as she affected a falsetto tone in mimicry. “‘What’s your brother like?’ ‘Has he always been so big?’ ‘Have you ever walked in on him when he’s hoofing himself?’ ‘How can I get a date with him?’ ‘Why won’t he ever chat with me in the halls?’”

“Uh…”

“Seriously, even Principal Cheerilee told me I had to keep an eye out for you: ‘You’ll need to keep a close eye on him, Cookie. This town hasn’t had a colt like your brother since Big Mac… and even a lot of mares around town prefer the color pink to Mac’s black.” Cookie snarled her lips and clicked her tongue. “As if I didn’t realise she was talking about scoring you for herself.”

“I, I really think you’ve got it wrong Cookie.” Caisson gulped, ears folded back. “I haven’t even spoken with a filly, let alone had a date with one. A girl wouldn’t be caught dead with a big, gross, lunk like me… even before they saw this, this thing between my legs.” He shuffled his hind leg with frustration, spitting the word with venom. Why was he cursed with this body?

“Uh huh.” Cookie deadpanned, staring at him. “I’m starting to think maybe you aren’t so good at reading a filly, big bro.” She chuckled, her tail flicking a little bit higher.

“I know I’m not.” Caisson groaned. “Just one more thing that’ll pretty much guarantee your brother will end up a kissless bachelor who’s good for nothing put plowing.”

“Pft.” Cookie rolled her eyes at him before quickly snapping her attention back to underneath his barrel. As her pupils widened once again as they fixed upon his shame, Caisson swore he could see her chew her lip as her tail hiked ever so slightly upward. “Well, after hearing from basically every filly and half the mares around school today, I’m sure you’re going to get very good at plowing, BC.”

“E-every filly?” Caisson’s head tilted. His brain was having a little trouble computing what his sister was talking about.

Cookie’s eyebrows knitted together, her nuzzle forming into a bit of a snarl. “I had to bite my tongue most of the day. Seriously, who do half those randy tail-flippers think they are? They don’t know the first thing about my big brother!” She stamped her foot, tail flicking upward in its semi-flagged position. “They’re treating you like some piece of meat and not the wonderful, kind, caring stallion you are! You’d better believe I’m not just gonna let any tramp get near my brother just because he’s some sort of trophy, they’re gonna have to do it proper — treating a stallion like a mare should!”

“Um.” Caisson mumbled, blushing at his little sister’s possessive outburst. “I… I don’t think anyfilly will ever get to know m-”

Cookie clicked her tongue and stamped again. “There you go again, BC. You really don’t understand a filly’s heart. Even with the number of shameless tail-flaggin’ post-grinders asking after you, you can’t just expect a girl to trot up to you and give you a hoofie...”

As she spoke the words, her ears folded back and that strange shiver rolled through her again, like some thought had just sprung into her mind. Caisson watched his little sister’s eyes flick from his stallionhood to his face a couple of times, as she toyed with one of her hooves on the barn floor, pawing idly at the dirt. He watched her, trying to understand just what she was thinking, looking from her hoof to his underbelly, when she suddenly winced and snorted.

“Ummnf!” Cookie squeaked, a red flush washing her face.

Caisson had been focusing on her eyes and hoof, and so he only barely caught the strange shimmering squirt of motion that came unexpectedly from her backside. Again that overpowering stench swamped the air of the barn — it had never felt so stuffy in here, not even during the height of the mid-summer heat.

His stallionhood throbbed, hot blood pressing against its fleshy-pink skin.

“A-anyway…” Cookie quickly chirped, quickly drawing his attention away from her rear. “Time to get your bellyband strapped in, BC.”

“C-cookie…” Caisson began to choke out, his mind scrambling for the words to tell her to stop. The belly-strap would go right across the midpoint of his shaft — harnessing this final piece would bring the young teen directly into contact with his painfully rigid erection. “I-I don’t think…”

“Now this’ll be a bit of a pickle.” Cookie hummed, ignoring him as she stepped in and took hold of one side of the loosely hanging belly-strap. “Seems like you’ve threaded your needle through this loop here.” She grinned, eyes not leaving the area underneath him. “And we can’t buckle your winky-wee underneath the strap that would pinch like a-... what?”

Caisson couldn’t help giggling. “Winky-wee. Haven’t heard you say that for a while. It’s cute.”

Cookie blushed again, blowing a snort out of her nostrils and stamping. “Hey, I’m a big mare now!”

“I know.” Caisson grinned. “‘Winky-wee’ just reminded me of when you were a foal, is all.”

“Cock.” Cookie sniffed, flipping her nose up. “You’ve got a buckin’ huge, mare-splitter of a drippin’ horsecock, BC.”

Hearing those words come out of her mouth was stunning, Caisson swallowed, trying to stifle his reaction. Why was hearing her say that so exciting?

“See? I can sling dirty words just like any of those trashy fillies at school. Hmf.” Cookie swung her head disdainfully. “Now, like I was saying. No way I can buckle you in so long as your cock is, uh, stickin’ up.”

“Can’t we just undo the bellystrap completely from both sides and then —”

“No way, that would shift everything I’ve already set.” Cookie quickly cut him off. It seemed to Caisson her eyes were a bit too spritely, nervously dodging meeting his gaze. “I’d have to start right from scratch, that’d take ages.”

“Uh, I guess.” Caisson hesitantly agreed. “J-just give me a couple minutes to calm down then, and the —”

“I just said we can’t wait any longer, BC.” Cookie huffed, still scrunching her nose and looking away from his eyes. “I don’t want Mom and Dad thinkin’ I’m the cause of you being late out to the fields on the very first day I’m strapping you up.”

“Well, what do you want me to do?” Caisson groaned, exasperated and embarrassed.

“Can’t we… y’know… take care of it?” Cookie finally looked at him as she said it, a blush on her face as she made a slow pumping motion with her right forehoof. “If you hoof one out won’t it go down?”

Hoof off? In front of my sister?

Caisson felt his cock jump and slap against his belly — just why did that excite him?

“I dunno Cookie, I shouldn’t do that in front of you.” Caisson mumbled. He knew he had to say the words, even though he was somewhat interested in doing that in front of her. Something about those big blue eyes, having them watch him… “Maybe if you stepped outside. Kinda weird that you know I hoof mysel —”

“Oh please, like Posey and I don’t hear you grunting and bumping against your wall every other night.” Cookie rolled her eyes. “Gimme a break.”

“O-ok.” Caisson gulped. “I guess I can.”

“Do you need help?”

The question was like a thunderbolt in his ears, clearing all other thoughts out of his mind. The surge of adrenaline made him almost kick a rear leg reflexively.

His sister… helping?

The images were too potent to hold in his mind’s eye, though they burnt into his neurons.

“W-what? N-no, I know how to —” Caisson stumbled with his words.

“I mean,” Cookie started to fumble her words herself, babbling just like she had earlier. The words started to spill from her fast and faster “I’m just thinking you’ve probably never done that in a harness before. Hoofed off I mean. At least, not that I’d seen. Not that I’ve ever seen you hoof off at all. But I just thought, you know, maybe with the straps you might get all chafed, might not be as easy to turn around, and since it’s my job, right, to help you out...”

Her ears were folded back, her face blushed, her eyes misty: it was clear that she had really wanted him to agree.

Caisson blinked, looking at her. She was so adorable, so vulnerable. It was so clear that she wanted with her entire being to do this to him.

For him.

He also knew that it was his duty as a big brother to say no. To stop this train before it left the station.

But there were also her looks. Her beautiful muzzle with its painted stripe, her ruffled fur, her mane and tail, her tight little rump. It screamed to something else in him, an ancient pride — this mare wanted to do that for him.

And that smell.

The thick aroma was like a cloud in his thoughts, as if the very air he was sucking into his nose was filling up his skull, getting in the way of every one of his neurons as they tried to fire.

So, when that moment came for him to say no...

He didn’t.

They stared at each other for a long moment.

“B-BC…” Cookie whispered, looking up at him. Those eyes were so deep, so blue. And there was a fire burning in those dark pools — a raging want.

Caisson felt his cock twitch again, and this time a wet trickle of his own spattered against his own chest fur, dropping in a heavy, sticky strand to the floor below.

Cookie noticed. Her nostrils flared wide and she shut her eyes with a contented hum, like a half-awake pony getting their first whiff of coffee in the morning.

“OK.”

He wasn’t sure if he said it or she did. His mind was in complete shambles. Thoughts of guilt, excitement, and instinct all competed millisecond by millisecond for his headspace — leaving only pure reaction and sensation as the siblings began to cross that forbidden bridge.

He was brought back to the present by the touch of a hoof against his stallionhood, the press of Cookie’s hoof-edge against the very large base of his shaft near to his testicles.

“Neeee-ah!” The whinny escaped him unbidden, his body stiffening and his cock bouncing under him as his pelvic muscles clenched and released. One of his rear legs stomped menacingly.

“Ah, sorry.” The hoof pulled back. “D-did I do something wrong?”

“No! I was just, ah, surprised.”

“Ah.” The hoof came back, quickly.

My sister’s hoof.

On my stallionhood.

His heart thumped hard enough that he thought it was going to pop in his ribcage. A filly was touching him. On purpose.

Cookie’s hoof pushed in harder, bringing the soft under-belly of her frog into contact with his pink heat. She began to rub back and forth, only an inch or so up and down, never straying far from the familiar territory where her touch had started. Uncertain, inexperienced.

Amazing.

“H-how’s that…?” Cookie breathed as much as spoke, curiously looking at him, hungry for feedback.

“Mm… C-cookie,” Caisson groaned. There was an element of embarrassment to this, sure. A sibling giving you an awkward hoofie in the barn, somepony he was so close to suddenly entangling with him in such an intimate way. But it was quickly being overtaken by a feeling of pleasure. “H-higher…”

It was all he could manage without devolving into a blushing, guilty mess.

“L-like this?” Cookie started to rub along his shaft closer to where the sheath connected to his belly, the top of his stallionhood — the dorsal surface.

“N-no… up.” Caisson gulped, letting out a soft breath as he accepted the sin, the wrongness of what they were doing. “Up. Near the tip.”

“Oh.”

The hoof began to trace its way up his rigid log, never leaving its surface as it slid, inch by inch, over his pink girthy base, up to his medial ring.

“B-buck.” Cookie whispered, just as her hoof slid over that muscular ring of flesh.

“What?”

“Just…” Cookie nervously replied, her ears flicking over to him, as she realized her invective outburst had been caught. “Y-you’re… just so b-buckin’ big.”

Caisson felt her lean some of her weight against his barrel for balance as she lifted a second hoof off the ground. With this new hoof available for use, she pressed against his shaft, on the opposite side of where Cookie’s original pleasure-paw had paused on his medial ring. “I can’t even wrap two hooves all the way around at the ring.”

A grasping squeeze of her hoof confirmed her observation, neither of the filly’s hooftips managing to touch around his huge erection, even at the midway point. The sensation of constraint brought another rumbling nicker through Caisson’s belly. He felt the sensation of squeezing pressure in his sack, his muscles pushing against his prostate. The twisting tightness inside his heavy balls from his swollen epididymis was brutal: he had never felt so full.

The ripple raced up through his stallionhood, erupting from his tip in a heavy splatter of clear pre-ejaculate. He’d never had pre-cum like that. In such abundance.

“Sorry.” Caisson groaned.

“You better stop apologizing for being so well-hung, BC.” Cookie giggled, sticking her tongue out at him — a reprieve from the anxious sanctity of their whispered silence. “It’s like saying ‘sorry for being so awesome’.”

“I was, uh, apologizing for…” Caisson blushed, embarrassed. “Dripping.”

“Oh?” Cookie slid her hoof all the way up to the orifice in question, running the delicate pad of her left hoof right over Caisson’s glans and smearing the clear fluid in question all over her hoof.

Caisson groaned. The explosion of sensation was too much for such a tender and erogenous bundle of nerves to handle such direct stimulation. He felt his left rear leg lift a few inches off the ground, kicking out slightly.

“I don’t mind — it smells amazing.” Cookie didn’t notice, still rubbing his stallionhood’s head. “Your drippings, I mean.”

She would have plenty to explore on him.

His bulbous end was as wide across as a saucer-plate, a huge crown topographically adorned with two prominent mound-sized protuberances, all separated by a milkshake-straw-sized urethra right in the lower center.

A stallionhead.

His little sister’s hoof was soon wet with the sticky-slick dribble that effused from him, as she swirled in circles that went wider and wider… until she was massaging the nubby bumps of the edges of his glans — which were quickly throbbing to a painfully engorged state.

“Oh. Oh…” Caisson groaned. “C-cookie…”

“Good?” Cookie smiled nervously, her hoof starting to find a rhythm. “I’ve never done it before, so —”

“It’s real good, Cookie.” Caisson breathed out, closing his eyes for a moment to just savor the feeling.

“Are you close?”

Caisson let out a breath through his nostrils. He wasn’t exactly a quickshot. From what he’d heard from other colts and sex-ed classes, stallions didn’t take much time to reach the golden plains.

Unlike them, he usually had to dedicate a good twenty minutes of ‘private-time’ in his room to climax. Time that he would usually have preferred to use sleeping. In his opinion, those other colts had it lucky.

“Just keep going,” he moaned, half-smiling to encourage his little sister.

Cookie chewed the inside of her cheek, eyebrows knitting in concentration. “Not my fault it’s taking so long.” She must also have some sense that his endurance was long — she’d taken health-ed too, of course. “It’s just so… big.”

Once again she leaned into his barrel to balance herself, allowing her to bring her second hoof back into play. Now Caisson’s head was trapped between two underhooves, each stroking with little tugs, back and forth. Cookie’s soft underhoof flesh was almost maddening against his delicate sexual tissue as she simulated the sexual grasp of a marehood.

That now-familiar ripple shuddered up from his aching testicles, as another heavy spurt of hot, clear, pre-ejaculate splattered out over his sister’s hooves and foreleg.

“D-did you… uh...” Cookie paused, pulling one hoof off of the tip and lifting it closer to her face for inspection. “Pop?”

“N-no. Sorry.”

“Stop apologizing.” Cookie giggled. Caisson watched as she brought her hoof up to her nose. “I love your smell, BC. It’s so… rich.” His heart skipped a whole beat as her lips parted and her tongue darted out to touch the slickness on her frog.

“MmmMM.” A deep hum escaped Cookie’s throat, and then rose in volume. Immediately her tentative taste became a deep lick — like a pony might do to clean a wooden spoon of thick, creamy frosting. Caisson watched his little sister’s eyes rolling up in their sockets, just before they were covered by her fluttering eyelids. All at once, she trembled, a shudder that shivered down her spine and into her rump. Her hindlegs braced, spreading wider in their stance and bending slightly, before her tail shot up straight in a fountain of flowing hair.

Splat!

There was no mistaking the source of that wet sound this time. Caisson saw the clear, steaming splash of fillycum squirt out from between his sister’s legs, splattering into a wet puddle onto the dusty floorboards of the family barn. A gossamer thread of her nectar drooled from her behind, connecting her to the spreading dampness in a long, slick, strand that belied just how lubricating his sister’s natural love-juice was.

“Ahn! B-buck!” The shudder worked its way back up his sister’s spine, making her back arch up and down, pivoting her hips up and down in an unmistakable wiggle-hump, before her left hindleg kicked out wildly at the empty air. She snorted, her head thrashing left and right.

And then it had passed.

Her eyelids re-opened lazily and uncoordinated — first one, and then the other. Cookie’s pupils were dilated and wild. Hot, heavy breaths puffed in and out of her open mouth; her tongue hungout like an exhausted husky. As those rolling, drunken eyes blinked and tried to focus on his face, her panting muzzle broke into a contended smile.

“D-did you just...?” Caisson breathed, echoing the question she had asked him only a moment before.

“Oh, BC.” Cookie purred, a tone he’d never heard from his sister before. She leaned into him, nuzzling her nose hard up his shoulder, practically grinding her snout into the muscular cord of his neck. “Yes.”

He had just made his little sister cum!

The thought made his cock jump in her hooves. She’d exploded onto the floor from tasting him! Gone were any thoughts about how wrong, how improper, how taboo this was. She was a filly. He was a stallion.

That was all that mattered.

Her neck-nuzzling face turned up toward his, as he craned his own head down to hers. Her eyes were sparkling, wild and drunk all at the same time — pupils blown wide by whatever flood of orgasmic pleasure was still boiling through her brain.

Goddesses she was so cute. So beautiful. So sexy.

So kissable.

He leaned down, his lips already starting to part as he did. He lifted a hoof to cradle the side of her face, his huge hoof wide enough to cover from her jawbone up to her ear, as he softly petted her cheek.

“BC…” Cookie breathed, close enough now that her warm breath washed over his nose. With her dreamy eyes, she took one of her still-stroking hooves off of his stallionhood, grasping his own massaging hoof, pinning it tighter against her own cheek.

“Cookie…”

They were just about to kiss, noses already touching, when physics once again reared her unforgiving head in Caisson’s love life.

Ponies were meant to have four hooves on the ground. By mathematical extension, two ponies should have eight hooves on the ground. Currently, Caisson and Cookie, in their incestuous hoofjob-kiss embrace, had managed only five hooves making contact with Mother Equus.

It started slowly, as their combined center of mass escaped their much-diminished area of equilibrium, the uneasy feeling of falling somehow mingled perfectly with the exciting feelings of forbidden love and arousal as they began to fall. Like a mighty redwood felled by a lumberpone taking a nearby sapling with it, Caisson and Cookie’s tumble accelerated faster and faster as they crashed to the ground.

A cacophony of limbs, hair, touching body parts and shared body heat arose from the rising cloud of dust that exploded up from their collapse to the barn floor.

They’d fallen on top of one another.

Cookie was the first to start laughing, a giggling chuckle that turned the corners of Caisson’s mouth as well. All of a sudden, both of them were laughing. Forgotten was all the cloying anxiety of moments before, now a stream of warm, happy emotion poured from them — the happy rush of accomplishment after one faces one’s fears and leaves them behind.

Caisson somehow found himself in a supine position, his back lying on the warm hay-strewn planking of the Harvest family farm. His diaphragm bounced up and down with each guffaw escaping his smiling lips. This bouncing quickly made him acutely aware of where his sister had ended up after the tumble.

On top of his chest.

He looked down at her, laughing carelessly, tears of mirth also forming in her eyes as she similarly shuddered with delightful giggles.

Shudders that Caisson could feel.

In a very sensitive area.

While physics could be cruel, she could also be playful. The precise balances and momentum-changes of their fall had brought Caisson’s little sister, barely half his size and mass, to a soft landing laying right across his cock.

The soft fur of her belly and chest wrapped around every bit of his fat stallionhood shaft, sandwiching him between his own underside and hers. He could feel her body-warmth through the furry coating, her body rubbing along his sensitive nerves with each giggling bounce.

“I guess we’re both a bit klutzy.” She choked out, clearing the mirthful tears from her eyes. She looked down, bringing her nose-to-head with his half-flared head. “Well, would you look what I found, big bro.”

Caisson’s sighing grin became a moan of sensation as Cookie began to slide up and down on him, using her whole body as a biological chamois to polish his heavy log of stallion-flesh.

“Cookie…” Caisson managed to mumble again, his breath quickly being taken away by the pleasure from feeling his little sister’s body rubbed against him, running every little rib-bone and belly-muscle over the aching ridges and veins of his penis.

“Have ta’ use my whole body to handle you, big bro.” She looked up at him with a grin, her body still pressing into him, clenched by the arms she was wrapping around his barrel. “Although, maybe it would be better…” She bit her lip, eyes widening as that rougishtwinkle appeared in her eyes again.

Caisson felt her plant a sturdy hoof on his chest, just above where his massive cock stretched. Pushing down against him for leverage, Cookie pivoted herself upward, raising her upper body so that she was straddling him upright, one rear-hoof on either side of his barrel.

“Oof.” Immediately Caisson felt the previously distributed weight of his sister’s svelte body concentrated on one spot — where her butt rested on him, just below his medial ring.

She swung her other forehoof forward, bracing herself on his chest with both forelegs , looking almost like a cowpony might when saddled up on a bison — if the bison’s back was actually a supine, painfully-erect stallion, that is.

“How’s that feel?” Her mane was falling down from either side of her face, hanging down toward his face.

He’d never been under Cookie before. Hay, he’d never had any pony looking down at him for years now. Even though he could easily throw her off with his tremendous power and bulk, there was something appealing about having her on top of him. Something hot.

“It feels…” Caisson paused, being under Cookie wasn’t the only thing that was hot. He felt the place where Cookie’s body rested on him, the spot on his shaft just below his medial ring. It wasn’t just warm, like before. It was hot.

Boiling.

His gaze slid down Cookie’s body, from her cute little belly-button… along her slender lower-abdomen. She had a small set of nearly flat teats, pert little breasts that were perfectly-sized for a filly her age. On the peak of the cute pair of mounds was a dark nipple, painfully erect. Little eraser-shaped nubs that hinted at just how aroused his little sister truly was. His eyes continued downward...

That’s when he saw it for the first time — Cookie’s fillyhood.

The sparse tuft of fur just above her lips was sopping wet with arousal, the furry hair-strands slicked together in chaotic cowlicks from the thorough soaking they had received. Just below, the fur gave way to a set of plump, slick, lips. The bare skin was far darker than Cookie’s usual skin tone — almost black as Luna’s winter solstice, though they shone with a glistening wetness. Even as he watched, the dark folds throbbed from Cookie’s heartbeat, engorged with her life’s essence…

Her dark pussy-lips made the next feature stand out with stark, almost blinding contrast. At the crest of Cookie’s fillyhood, a striking flash of pink drew Caisson’s eyes — his little sister’s clit! He could feel the bit-sized lovebud as it pulsed out from her tight folds, slipping in and out with every other heartbeat, without ever retreating all the way back into its velvet cave. And with each pulse, the heart-shaped nub would slip along his shaft, touching his stallionhood and leaving a small, wet thread of honey behind.

And then, those dark lips were wrapping around his shaft-top, spreading so wide as to reveal the boiling-pink inner-labia of his little sister’s fillyhood, though they couldn’t cover more than a part of the ventral thickness of his cock.

It was like he was looking at a pony trying to wrap a dinner napkin around a redwood — it barely reached the halfway point.

“W-wet.” Caisson finally managed to fit his tongue back into his mouth after it had been hanging out in pure marveling appreciation of the sight of his sister straddling his dick.

“Mm-hm.” Cookie’s eyes were sparkling with that fierce hunger again. Her mouth slacked open, as she let a steamy breath slip over her lolling tongue. “I’m gettin’ a little… worked up… myself.”

“Y-yeah?”

“W-why don’t we… help each other?” she breathed, looking down at where her tight teen twat was straddled astride his shaft, before raising those ferociously hungry eyes to meet his face.

“Ok,” Caisson swallowed as much as answered. There was no way he could even think, let alone protest. He started to lift his arms up.

“No,” Cookie’s hooves moved from his chest to his shoulders, pinning them down. “I got this…”

Caisson nodded, heart pounding. Cookie was in control.

And that’s when she started to grind.

The sensation was indescribable. It was like a hot, wet, viscous, silk grasp sliding up his cock. Every bump and vein slid against her sex, eliciting shudders and whimpers from her as she continued to slide closer and closer to his face.

Both of them synchronized a grunt as Cookie’s clitoris bumped against his medial ring, forcing it to compress before it finally slipped over the prominent ring of stallionflesh, followed shortly by the furnace-like heat of Cookie’s pussy. Although she had already been leaving a sticky-wet, shining trail of filly-nectar in her wake, that particular bump had made Cookie follow her grunt with a squeak, a sudden humping of her hips… and a copious river of additional honey that spilled over either side of Caisson’s belly and dribbled onto the barn floor below.

But still, she kept grinding upward, inch by inch, pink on pink. She was approaching where the flat broadness of his ventral shaft finally started to narrow, giving way to the pronounced ridgeline of his corpus spongiosum, which put even more pressure on his little-sister’s pleasure-button as her slick lips began to slip around more of his tapering penis.

“Ahn… Ahn!” Cookie’s squeaks were becoming less intelligible now, her eyes alternating between closed and open, pupils rolling wildly. Her body was moving more erratically, pausing in its grinding journey to hump more fervently against his stallionhood, satisfying her insistent erotic itch and bringing the little filly closer and closer to a trembling conclusion.

That’s when she reached his cockhead.

The tapering flesh of his shaft, though still tremendously wide, blossomed out into the huge battering-ram that was his knobby head.

His little sister didn’t even hesitate; shifting a more weight onto her front hooves, she lifted her hips ever so slightly, clearing the almost cliff-like transition to move her grinding sex up onto Caisson’s flare.

“B-buck…” Caisson groaned a curse through clenched teeth as she ascended, feeling his sister’s love-bud grind against his glans, sliding its novel, slick-flesh, feel up and across his urethra — such a strange, yet intensely erotic act… and he was doing it with the filly that he’d been a big brother to for years. They were about to mash their excited sexual bits against each other with wild abandon.

And then she pressed against him.

Those wet nether-lips strained and stretched to slide over his hoof-sized cockhead, slathering his sensitive glans and flare-edges with soaking, sparkling sensation.

“Oh, f-fuck,” Cookie gasped. She was swirling her slick teen cunt all over his head now, as though it were some wet paintbrush and she didn’t want to miss a spot.

“C-cookie…” Caisson moaned in reply, resisting the growing urge to grab her by her hips and yank down. But he couldn’t resist the jumping pulses that were making his stallionhood jerk and bounce, each time releasing copious splashes of his own pre-ejaculate fluids.

“BC!” Cookie squeaked, tossing her head back and pushing down hard. Caisson could feel the filly’s inner-lips parting, stretching. The bulging protuberance of his glans was almost slipping inside her! It was so tight.

So impossibly tight. The angle was all wrong, her slipping along his head instead of on top of it — even if she was aligned there was no way her tight teenage pussy could admit his freakishly huge head. And yet there was no denying it.

His little sister was trying to impale herself on his cock!

Caisson was in a state of disbelief. Cookie was trying to stuff his huge beast into her slender little snatch! His little sister, who he’d always known to be so cute, innocent, diligent. A beacon of good-behaviour, a filly he would ruffle the mane of and tease across the table. She wanted to fuck him, wanted it so bad she was grinding herself against his flare!

And he wanted it too.

His hooves dug into the floor, trying to find something to grasp as he resisted just throwing his sister to one side and pounding into her.

“B… BC!” Cookie’s squeaks were getting wilder and higher pitched as she started to thrust wildly into his flare.

“C-cookie!” He could feel his stiff urethral bump protruding into the forbidden tunnel just inside those tight inner labia, splattering his pheromone-laden pre-ejaculate into her body. So close! They were so close.

“Ah! AH! C-C… Caaaaaaaaaseeeeeee!” Cookie’s spine arched backward, curling like a broken spring winding up on itself, her head tossed backward, chin pointing toward the ceiling as her mouth fell open into a groaning scream of his name, Caisson, something she had never called him.

As Caisson watched, the wild spasm wracked through her body, a ripple of rising fur flowing to the extremities of every limb, even causing one of her hind-legs to kick wildly along his side.

And then he watched her delicate teenage fillyhood flower.

A powerful wink sent Cookie’s clit shooting outwards, farther than it ever had before, peeling back her marelips with potent contractions that squeezed and released in milking throbs, over and over.

And with each throb came a flood of steaming filly-juice.

Her humping hips seemed to pump even more of the oh-so-delectably fragrant nectar as it splashed all over his chest. His belly was soaked with Cookie’s fillycum — a hot, sticky mess of her perfume as she emptied her lubrication all over him.

Her orgasm seemed to hang for minutes before the clenching convulsions started to give way to a muscle-melting release, the added lubrication making her backslide down the long length of her brother’s cock as she melted away from her rigid, peaked posture.

“Ahnn…. Big brother…” Cookie’s contented hum as she slowly slid down him was but a tiny window into whatever pleasure cocktail was melting her neurons. Caisson had never heard her, or any mare sound so satisfied.

As she slid down him, he felt each bump she’d crossed on her way up, now kissed by her tight, athletic buttcheeks… and a strange kiss of hot flesh that he could only assume to be her hidden tailhole.

Inch by inch she slid back, mewing in post-orgasmic contentment the whole way… until she finally bumped back against his heavy balls…

Now painfully tumescent: Caisson had heard fromhis colt-buddies about the painful legend of ‘blue-balls’ (which always provoked a goofy joke from Hay Bale, who had blue fur to begin with), but this was the first time he was feeling that painful tightness in his gut.

Cookie’s little sister sat upright, resting her little teen butt on his heavy sack. He could feel the hot trickle of Cookie’s drooling fillyhood pouring over his balls, coating them in a layer of her sticky nectar.

“Ahhh…” Cookie sighed happily, still coming off her orgasmic-high. Caisson had to smile to himself — she looked so cute, so rosey with warm satisfaction: like some kind of sexual tabby that had been slipped a sack of cat-nip.

“Feel better?” Caisson grinned.

“Ahn?” Cookie’s face slowly reset as she roused and returned to herself. Quickly, her embarrassed blush returned as she realized her big brother was watching her. “Oh… y-yeah. Did you not, uh-?”

Cookie’s eyes scanned down, inspecting his stallionhood.

“Nope, but that’s OK,” Caisson sighed, reaching down and pumping himself a few times absently. “Sometimes I take a little longer to... y’know.”

“Now that ain’t fair, BC.” Cookie’s brows knit again, her tongue protruding from her lips as the fire in her eyes fanned back into flame. “Hooves off, BC. I got this.”

Cookie reached down with her hooves, slipping them underneath his heavy lower shaft, then starting to pull his girthy, massive stallionhood up, like she was erecting some kind of erotic, pink-flesh flagpole atop the Canterhorn. Inch by inch it swung up, faster and faster until it met Cookie’s chest with a meaty, wet, slap.

*THWAP*

“Celestia’s Mercy,” Cookie Whispered, looking down at Caisson’s monster against her body, “You’re right up to my ribcage.” The words escaped her in soft wonder — Caisson thought he was seeing a little bit of fear there as well.

“Y-yeah.” Caisson mumbled. The sight before him was obscene: his little sister basically hugging his sapling-tree-trunk sized stallionhood against her body, the tip coming up nearly two-thirds along her smaller body, as a wet patter of his pre-cum burbled into her chest-floof.

“You must be what, twenty inches? More?” Cookie chewed her lip, those eyes of hers flicking between an almost indecipherable mix of excitement and fear.

“I dunno.” Unlike many of his colt buddies, Caisson had never measured himself. He dreaded the confirmation of freakish size that the yellow tape would surely yield.

Cookie’s eyes flashed up to him. “You’ve never measured?”

He shook his head.

“Liar. Every colt measures.” She huffed, her hooves starting to slowly slide up and down his stallionhood, pressing his rigid shaft into her teats, then her belly, then her chest as she moved the force of her hug up and down his length.

Caisson’s mouth dipped open, surrendering to the sensations of having another pony... a filly... his little sister masturbating him.

“Hope Hammer said you were twenty-three and three-quarters long, and about eighteen around.” Cookie grinned, her hooves starting to move faster and faster. Long, powerful strokes that raced up and down his whole length as she pulled more and more of him into her body. “About as girthy as a barn-beam and longer than stud-spacing in walls. Hope’s special talent is carpentry, so all the fillies use her to compare the boys’ sizes at school.”

“Mmph!” Caisson groaned, the tightness is in his gut twisting tighter and tighter, like an overwound clock-spring, straining against its mechanisms. His whole stallionhood was throbbing, it had never felt like this. He’d never edged so close to orgasm then backed off at the last moment. This treatment was making him feel like his the pulse of engorged blood beneath his straining shaft-skin might burst.

“None of the other colts even come close, by the way.” Cookie smiled, her eyes simmeringwith desire. “I’m one proud little sister, because every filly knows that my big brother has the biggest…”

She pumped harder.

“... Meatiest…”

Another hard pump, her hooves working closer to his flare now, bumping and running along those glans and knobby ridges that were packed tight with sensitive nerve endings.

“... Sexiest…”

Swirling all over his flare now, urgently tugging his coronal ridge, pumping up and down with maddening, demanding, strokes.

“... buckin’ mare-splitting stud-cock!”

He’d never heard his sweet, innocent little sister use language like this. He didn’t even know she was capable of thinking language like this! It was so wrong — and so blazingly exciting! Her words were like a feral growl, like he was seeing the delicate outer disguise of Cookie stripped away — to reveal the lusting need she had as a mare underneath. For him.

Her big brother.

Her hooves had stopped pumping, grasping tightly now under his flare, squeezing him like a tube of toothpaste.

“And my big brother’s big fat pink cock belongs to me.” With this proclamation Cookie’s head dipped downward and her lips parted. Caisson watched, unbelieving. It was like time had slowed, an erotic trainwreck moving in slow motion as his sister’s burning blue eyes’ intense focus bore down on his drooling cockhead.

Her tongue slipped out from her muzzle just before it made contact, like a pony taking a huge, languishing lick of a dripping ice cream cone… and then he felt it: his little sister’s tongue against his cock.

Her pink oral-muscle started just below his throbbing glans, drawing up across his burbling urethra before sliding in a rough swirl across the remainder of his saucer-sized flare. And the intensity just ratcheted up from there — it was as if the first taste had made his little sister desperate for more.

Her mouth got closer, lips engulfing what little they could of his massive tip, suckling his throbbing cock-slit as her tongue ran wild, lapping against him with obscene slurping gulps.

“Oh FUCK!” Caisson grunted, his hips lifting up off the ground involuntarily. “Cookie!”

Cookie giggled into his cock, her humming laugh vibrating against his glans as she continued to lick her big brother’s flesh ice-cream cone treat. Her hooves started to softly pump once again, coaxing him as she attacked him with a novice’s enthusiasm: wild, uncoordinated licks and kisses that came faster and faster.

“C-Cookie!” Caisson grunted, meaning for it to be a warning. He felt something deep in his gut twisting, turning, breaking. That spring, so tightly wound, now starting to break and snap, about to release all its stored up potential energy. There was no stopping it now.

Cookie was just going faster, harder, more desperately. Her tongue was sucking right from the source of his leaking pheromones, and it was like she was a thirsty Saddle-Arabian fresh from crossing the desert at an oasis. Gulping and slurping.

And yet she still wanted more of him in her — he could feel her lips trying, futilely, to stretch enough to take in his whole stallionhead — an impossible task.

And about to become more impossible, as he felt himself begin to flare.

“AAAhhhnnnn!” The groaning scream escaped from Caisson’s mouth. His heart POUNDED out three consecutive beats, each feeling like he’d been kicked in the chest by an apple-farmer. Huge, heavy pulses of his cardiac muscle that drove massive waves of boiling stallion-blood through his arteries.

His cock throbbed, almost like a garden hose that had been plugged up, veins engorging and popping out as the surge of pressure flooded through his pink cock, turning it a dark shade that was almost red.

It reached his flare, ballooning out the already huge knob into something terrifying. Cookie’s eyes shot open as the stallionflesh in her hooves expanded and bulged, blooming wider and wider as her brother flared.

“Mmmf!” She gripped him and pulled him tighter against her mouth as more of his tip grew away from her capacity to hold it in her muzzle, leaving her just pursed against his urethra. Holding on for dear life.

“Ohhh F-F-UuUuuuuUuCk!”

The spring snapped.

Caisson felt his heavy, buck-ball sized testicles shoot up toward his sheath, smushing against his sister’s bottom as they retracted. A hedonic wave of overwhelming testosterone and potent neuro-chemical pleasure raced up to his brain where it exploded like fireworks on Midsummer’s Eve, flashing through his cortex with crackling sparks of pleasure that triggered a euphoria that he’d never experienced.

His thaumic system throbbed, ancient earth-pony magic energizing his every limb and muscle, bulging and powering muscle fibers and skeletal structures with powerful intrinsic life-giving vigor… including his sexual system — stirring the deep, primordial, biological advantages of the prolifically reproductive earth-pony race… flicking the hidden light-switch of the prehistoric alpha-stud harem-leader of Equus’s feral pony herds to on.

And then he came.

The first burst of stallion-batter blasted out of his cock, right into his little sister’s throat. A thick, carpentry-glue-like, rope of his steaming cum shot right into the back of her throat. The pulse lasting seconds as it emptied out of him.

Cookie’s cheeks quickly puffed out comically, like a squirrel holding too many nuts, as she was never going to be able to swallow her brother’s ejaculation fast enough. Finally, her lips cold hold no more and they burst the seal from his angry flare, spilling a deluge of frothing cum that spilled down her chest and his shaft.

She pulled her mouth from the throbbing cock, leaving an erupting jet fountain of splashing stallion-batter shooting up into the air, landing in heavy, sticky lines all over her mane, her shoulders, her chest.

Finally, the fountain cut off, tapering down.

“AHHG!” A second grunt, a second thrust of the hips. Caisson’s second spasm began.

Caisson saw his little sister flinch away, but still receive nearly a full on splatter of his second ejaculatory spasm, hitting her right with such impact it was like a paint-filled water balloon bursting on her. The stream of gushing cum was like a firehose against the underside of her chin, splattering off of her to cascade down in sheets of splattering cum to slather her belly.

“Ahh!” A third shot. Just as hot and thick, this time up in the air as Cookie had managed to push her brother’s exploding, mammoth, stud-rocket away from her. Lazy jets of Caisson’s potent seed flew up to splatter down on her mane, on his chest, all over them.

And then a fourth, and a fifth, all while he bellowed like a charging buffalo.

Caisson felt like his whole essence was being drained through his penis, pouring out volumes that he didn’t even know he had. He sometimes had big loads, if he had abstained for some time… but he’d never cum so hard before, with such clenching, powerful spasms.

Cookie was almost laughing now, playing with the rock-solid stallionhood in her hooves like it was some water-park cannon, directing it at different parts of her chest to coat her light-colored belly fur with her big brother’s genetic paint.

An eighth, a ninth. His voice grew rougher, his vocal chords strained from overuse, pleading for the torrents of cum searing from his cock to subside. A glob attached itself to the ceiling, suspended by gelatinous surface tension only to come tumbling down.

The shots were starting to lose just a touch of their intensity now, the streams not arching so high, the cream coming out thicker and more solid. Through squinting, burning eyes and with clenched teeth, Caisson watched Cookie sometimes direct a spasm into her open mouth, taking it on her tongue for as long as she could before having to direct her jerking cannon away once again.

A final, tenth spasm… dying down to a trickle that slid down the underside of his stallionhood.

“Aahh… hah… hah…” Caisson’s orgasmic aftershock began to relent, the spasms dying down and leaving strange ripples in their wake. And yet, something seemed wrong.

There was no happy, contented wave of pleasure that usually came after he climaxed. His heart was still pounding, perhaps even harder than before. His stallionhood, which usually softened quickly after a hoofing-off session, was still stiff as an oak-tree… maybe even harder than it had been before he came.

He buzzed with an energy through his every muscle.

“H-holy buck, BC.” Cookie half-chuckled, half groaned. She was working her hooves along her chest, trying to clean the absolutely cum-soaked fur. “Were you backed up or something?”

Caisson looked at her. Dripping in his seed. For the first time, he didn’t just see his little sister. This was a filly. A mare.

How could he have not noticed it before?

“Goddesses, you’re incredible, BC.” Cookie sighed, letting a hot breath escape her muzzle. As she wistfully looked at her stained, drenched body. “I just love your smell. Your taste. I don’t know why… its just so comforting… so stallionly.”

Caisson’s nostrils flared, as he listened to his filly talk about him. He could smell her. Drenched in his scent… but underneath that, was her. Her musk. That cinnamon-sweet spicy perfume that was coating his balls, that this sexy little minx had been flicking to and fro since she’d stepped into his territory.

She was in heat.

His filly was in heat.

How could he not have noticed before?

“Oh BC.” Cookie cooed, grasping his cock again with her hooves in wonder. “Wow. Just wow, and you’re still hard?”

And now she was touching his stallionhood. Playing with him. Wanting him.

“I love you, BC.”

A rumbling nicker escaped from his mouth as he surged upward, easily tossing Cookie backward in a tumble off of him as he stamped up to his feet.

“B-big bro?” Cookie looked up at him from her side, on the ground.

She wants me. She needs me. My filly. And I need her.

He stamped hard, letting out a whinney as he did so, standing stock straight. Now he was towering over his little sister, his huge, draft-horse sized bulk easily twice her size, huge muscles rippling and bulging along his barrel, his whithers, twitching through his flank and his neck.

He was in rut.

Rut.

The activation of nearly unstoppable biological impulses, cranking a stallion’s desires up to eleven, and drowning out any semblance of logic or reason.

He knew that his body was surging all sorts of earth-pony magic and male hormones and sexual chemicals to drive him to breed.

And he couldn’t stop it. He didn’t know if he wanted to stop it.

“O-oh… oh, big bro.” Cookie whispered, ears folded back in submission, her eyes dipping as she looked up at his feral, aggressive posture.

Caisson stamped again, snorting hard enough to scatter bits of hay that were strewn on the barn floor. His massive cock throbbed beneath him, slapping against his belly — his little sister looked up at it in a mixture of fear… and total desire.

Caisson watched her eyes flick from his dripping, throbbing stallionhood up to his face. He could see the excited-anxiety in those eyes: a swirling mix of that fiery sexual need, of a scared filly overwhelmed by a stallion in rut… and of an intense, little-sisterly love.

“Yes.” She breathed, clattering to her hooves and getting up on all fours, and turning away from him. “Yes, BC.I want this. I want it so bad, big bro.”

*CLACK* *CLUNK* *CLACK*

Caisson’s heavy clattering hooffalls were as sharp as drumbeats against the old oak floorboards, which creaked and groaned under his muscular size. His hooves were huge, so much bigger than Cookie’s as he walked over to her.

Cookie was panting now, looking back over her shoulder at him as he approached. With a little nicker and a turn of her head, she scampered forward, an excited-scared skip that brought her to the stacks of hay bales on one side of the barn, built up into a multi-level pyramid structure for later consumption. His little filly lifted her front hooves up onto the edge of the first bale, as if she were about to start climbing the structure to get away from him.

But then she tossed her head back again, that wild mane flowing through the air as she glanced over her shoulder again.

He could see that fire burning in her eyes, smoldering embers of lust fanned into an inferno that could consume the Everfree.

“I’ve been aching all day.” She flicked her white tail up, so high that her back quivered with the effort — she wanted him, her stud, to see everything. Despite the singular, primal drive thrumming through his rut-activated mind, the sight still made Caisson pause, flare his nostrils, and whinny.

Caisson let his eyes slip down the long, white strands of tail fur, to where they mingled with his sister’s taupe dock, currently flagging hard for him, wagging ever so slightly with excitement, like a happy puppy. The delicate underfur of her dock quickly ran down to a dark, almost pitch-black flesh ring, a muscular little ponut of flesh that quivered tightly.

Her tailhole.

It was so small and slender, just like her. Barely wide enough that it’s outer edges touched the athletically muscular pertness of her butt-cheeks. His gaze continued down, over that ring and across the desolate little patch of skin nestled between her tailhole and fillybits, which dripped with the humidity and heat that was rising from just below.

That’s where her plump fillyhood started. Those pitch-black lips looked so impossibly compact and tiny while paradoxically being puffed and engorged with his little sister’s arousal, all at the same time. He could see that she was tight, a small filly to begin with — and despite her pussy’s best efforts to expand and engorge, she was still a young teenager.

Her lips had parted slightly, pushed open by her permanently exposed and erect love-nubbin. Cookie’s clitoris was even bigger than it had looked when it was grinding along his shaft. The bit-sized heart-bud of swollen, nerve-stuffed, nectar-dripping flesh protruded out from the bottom of her teen fillyhood, a bright-pink signal that had peeked open her labia.

Through the parted folds, Caisson could see glimpses of his little sister’s tight, twisting pink interior. Her swirling inner-lips quivering and spasming, sometimes even betraying hints of the volcanic velvet tunnel within.

And then, as he was taking this in, she winked.

All at once that tiny, tight, teenage-pussy did its very best to show itself off to him — a clench brought the clitoris shooting outward and the muscular bottom of her pelvic floor racing upward, pursing out her energetic fillyhood. Those lips all parted for a moment, widening the still-minuscule tunnel just enough for a brief glimpse into the thrumming, hot-pink depths of her unexplored femininity… before it was occluded by a gush of steaming love-honey.

*Splat!*

A cupful of her hot fillycum splashed out from her depths, soaking her inner thighs and sending droplets scattering across the floor to soak into Caisson’s foreleg-fur.

“Celestia, I need this! I need you!” Cookie whined, lifting her hips up as high as she could. Caisson walked forward, his big hooves stepping easily around and over his much-smaller sister. Even though she was only a little small for a teenage-filly, Caisson barely had any trouble simply walking over and around her, his size meaning that he didn’t even really need to mount her.

*Thump* *Thump*

Caisson’s huge, unshorn-fetlock’d forehooves slammed down onto the haybale outside of his little sister’s. Hers were so small compared to his, so delicate. He lifted his big, strong neck up, before tilting his nose down to look at his filly. He let out a heavy blast of hot air from his nostrils, a wash of powerful stud-breath blasting against the nape of his sister’s neck and sending her mane flickering like white streamers.

“I fantasized… had always hoped…” Cookie shivered under him, looking straight up at him with those big, blue eyes, so full of want and need, “... hoped you would be my first, big bro.”

*Thwap!*
Caisson let his heavy stallionhood, still pulsing with almost unbearable tumescence, drop away from where it had been held rigidly against his barrel. It crashed down with a meaty, wet, slap against his little filly’s back, sending out a splattering splash of stallion-juices that had been accumulating on his dripping flare.

“Oh, Goddesses~! Cookie squeaked, her eyes flaring wider now that she could feel the sheer weight of his stallionhood on her.

His flare was nearly up at her withers, drenching the small furrow of her spine with the mixture of left-over ejaculate and drooling stud-honey.

Cookie! Caisson wanted to say her name, to call out his affection for his little sister, but the cry died on its way to his lips. Cookie!

Instead, a grunting growl rumbled up his throat. His consciousness was a faded spectre, a refugee bobbing in the churning waves of the tumultuous storm that was his mind. There was no gentleness, no hesitation in him anymore. Now he was a pure force. Love. Strength. Masculinity. Desire.

Instinct.

Caisson slid his rear hooves inside the stance of his sister’s hind legs deftly, quickly forcing her to spread them wider, lowering her posture and getting her to tilt her pelvis upward. She would need a wide-stance to accommodate what was coming.

Clattering backwards, Caisson grit his teeth, supporting most of his weight on his upper limbs as he started to position himself. Inch by inch his gargantuan stallionhood slid down his little sister’s back, leaving a wet trail of passion in its wake as it bumped along each vertebra.

“Ahhn!” Cookie whined, quivering as the log-like base of his stallionhood slid along the cleft of her buttcheeks, smushing her dock to one side.

With a level of coordination that could only be attributed to the assistance of millennia of moons of ingrained genetic routine, Caisson slid his hips in such a way as to pull his stallionhood off of Cookie’s back, and into prime position for sliding into his little sister — though his instinct-compelled mind considered her his soon to be his brood filly.

“Caisson!” Cookie groaned aloud, like a madmare, pressing her own dripping, gaping sex back at him.

The hot kiss of her filly-cunt against his huge flare jolted him like a sparking cattle prod. There was no deliberation, no confusion in his consciousness. His primitive, well-oiled stallion-hindbrain was in full control. It had flooded the remainder of his cognitive system with irresistible androgenic hormones that overrode each and every synapse, interrupting his every forming thought to interject with a singular, insistent compulsion.

‘FUCK HER.’

Everything else was burnt away in the crucible of this wanton desire, all that was left of Caisson the gentle-stallion were those emotions that would be useful to fulfilling this biological imperative: the love he had for his little sister, the cute-beauty that he had always seen in her, the desire to protect and guide her, to make her happy… those emotions were all enhanced and focused, sharpened to a point that would be used by the potent and ancient reproductive neural pathway prerogatives to achieve their objective.

Fill this filly with your big fat cock and pump her full of your seed.

Like a well-oiled machine, his hind-brain took in the sensation of fertile, wet, ripe filly-flesh against his flare and channeled the neural pulses through high-speed, logical circuitry — all quite independent of any conscious layer of thought — quickly arriving at the solution: thrust.

His powerful muscles tensed and fired, driving his legs forward in a tremendous burst of raw, animal power. Even if Caisson had been harnessed up to a three stone-boat-sleds filled with granite flagstones he would have made the whole chain jump with the force that he tried to penetrate into his little sister.

His flare smushed against her wet opening, an impossible fit even with careful consideration, let alone a wanton penetrating thrust. Their mutual, slick genital-wetness caused the force of the thrust to quickly slide off Cookie’s pussy and race up under her belly.

“Ahn!” Cookie squeaked aloud, as the huge flare-ridge bumped against her throbbing clitoris before grinding over teats and up the underside of her belly.

Caisson felt his cock had missed its mark, confirmed by only the top of his mammoth stallionhood feeling the sensation of his sister’s body warmth. He growled in frustration as the sensitive head of his penis bounced up her underbarrel, finally stopping as his heavy hips bumped into Cookie’s and his huge, heavy balls swung up with leftover momentum to slap against the base of his cock.

“Ooomph!” Cookie grunted, taking the full impact of her brother’s thrust through her hipbones and bouncing forward against the hay bale she was propped against.

He had missed!

He fumed, blowing an angry snort out of his nostrils and stamping his foreleg. He didn’t even pause to consider that his cockhead was as far along as Cookie’s ribcage: if he had speared her with his goliath organ on that thrust, he might have knocked the wind out of her, literally.

Damnit!

“Whinny!”

He tried to curse aloud, but it instead came out as a terrifying growl-whinny, like an infantry-pony on the front line of a medieval charge. All his thoughts and actions were being converted into something more fierce, more primitive.

The rut was in full effect.

He quickly untensed his hind-legs, stumbling and shifting back to reposition himself, dragging the still-flared pink saucer of his cockhead up his little sister’s inner thighs. With a squeeze of his powerful pelvic floor muscles he tensed his stallionhood, making it rigidly lift for alignment once again.

He felt that brief, hot flash of teenage-snatch, and started to press forward. But he had already slid too high, instead pushing against the strange, bumpy ring-like tightness of a different orifice. The kiss of this tiny opening was very different from the other — it barely covered even a fraction of the surface area of his wide-flare… and there was no yielding in its clenched tightness.

“Whinny!” Now it was Cookie’s surprised nicker that shook the barn walls, directly communicating with him. “Stop!” Her left rear leg shot out in a violent, instinctive kick, glancing off the inside of his own rear leg.

Sorry!

“Snort! Huff!” His intended apology converted into a strange mixture of body movements, ear-flicks and breathing sounds.

They were communicating like horses now. Like tribes-ponies in the ancient plain-societies of Equestria, before their ancestors had become sophisticated enough to use words… and yet each little stamp and breath, each head-toss and ear flick, each clench, squeeze and drip… it was all as clear as if they were conversing on a debate-stage.

“C-caisson! Caisson! Please!” Cookie scream-whined, looking over her shoulder at him with an aching desperation in her eyes, like a drowning mare pleading for a life preserver. “I need you in me! Now!”

His little sister needed him to up his game… his broodfilly needed him. Now. Caisson quickly readjusted, bringing his cockhead down and back to the burning, pink gate of destiny, just as Cookie’s teen-pussy winked wide, her body doing its utmost to help her stallion, her stud enter her.

And it worked.

This time, the fat mound-tip of his flare embedded itself in his sister’s folds, not entering her, but capturing the furthest extremity of the overwhelmingly-large stallion-penis in its grasp…

And that meant that Caisson could push. The brain gave the go signal, powering up the bulky bio-mechanical machinery of the young stallion’s legs once again, this time with more caution and control.

He began to grind forward — not a wanton thrust like the first shocking touch against his sister’s dripping-pink flower... but a steady, increasing force like they might use when ratcheting out a tree-stump. Bit by bit he dialed up the intensity, transmitting all of the force of his fiercely strong legs, braced against the floor of the barn, up through his leg muscles, through his cock-base, up his shaft, and against that single point of contact where his huge flare mashed against his sister’s too-small filly-pussy.

“Ahn!” Cookie groaned, as she tried to brace herself on the hay bale with her locked forelegs against the tremendous force he was applying against her slender fillylips. “C-caisson!”

Her delicate folds were straining, stretching to accommodate his massive flare. Bit by bit, they spread outward, thinner and thinner, attempting to accommodate the bulk of Caisson’s cockhead. It seemed impossible — but mares are wondrous things, able to pass a foal’s head in childbirth… and this little filly’s body was ready to do equivalent miracles for her stud.

More! More!

Caisson’s stud-mind fumed, he did not want to be denied, not now! He pushed harder with his legs, driving his little sister’s body into the haybale pyramid, enough to make it tilt and sway dangerously.

But it was working.

Slowly, she was yielding… her tight young fillyhood expanding to meet the impossible demands of her huge mate. The wet heat of Cookie’s inner labia slid around the knobby edges of Caisson’s flare for the first time, enclosing him in a vise-like tightness of filly-flesh that sent a burst of sensational nerve stimulation into the big stallion’s pleasure centre.

*POP*

And then he was in.

All at once, hishuge head finally slid into Cookie’s pussy, her lips wrapping around the big flare and gripping the slightly narrower shaft underneath tightly. With the widest part of the top-half of his penis finally inside his sister, the powerful force both siblings were applying to try to cram as much cock into her small body quickly drove five inches into her body. Caisson’s cockhead was like a battering ram, bulldozing the squeezing confines of his little sister’s vaginal canal open as it plowed into her depths.

“MMmUGH! Holy buck!” Cookie choked out, like she’d been punched in the gut. “S-so big!”

But Caisson could hardly focus on her words — all he could do was bask in the sensation of perfect, wet, hot pink filly pussy welcoming his stallionhood. The swirling inner-folds of Cookie’s tight fillyhood clenched and whirled around his cock. It was so small and strong that the constriction was almost painful, and that was before his throbbing fullness would be squeezed by one of gripping, pussy-clenches that his sister’s body was firing off with regularity. But even that sensation was pure, white-hot pleasure.

And he wanted more of it.

Wanted more of himself inside her. He didn’t relent even an ounce of force from his driving rear-legs — never trying to withdraw even a fraction of an inch from the incestuous union they’d established — he’d go deeper, further, harder.

Slowly, the huge pink stallionhood sank into the squirming, squealing filly. Inch after inch of stud-meat grinding into her little body, each sopping bit causing obscene squelches and drips to emerge from Cookie’s plot.

“Ahn! AhhN!” Cookie’s head bent downward, her body tensing, focusing on accommodating her much larger older brother.

The shaft entering her now was starting to widen: Caisson’s girth started to grow terrifyingly as it approached his medial ring. He could feel his little sister’s clitoris grinding and bumping down the ventral side of his penis now, like it had before, except now he was stuffing her body with himself, which made the fat lovebud desperately strained against his unyielding rigidity. The bit-sized nub, stuffed with potent nerve endings, had been stretched into a crescent of throbbing, sensation-screaming pleasure… and it was booping and grating over his every vein and bump.

“F-f… Fu-ngh… AAAAAHH!” Cookie suddenly started to tremble and shake under him. Her tail lashed up striking his balls with whip-like, stinging force as she unintentionally tensed… then began to spasm.

He looked down at her, watching her head begin to thrash left and right, her muzzle biting into one of the binding straps of the haybale she was propped upon. And then her back started to arch and flex, whipping between convex and concave, wracked by powerful spasms… that went right through the powerful muscles of her filly-snatch.

She was orgasming.

Hard.

Milking waves of grasping, suckling muscles pulled and released the whole of his twelve-inches of embedded, gigantic, pink-hot, studly penis. Each thrum of her aching velvet-tunnel was a perfect milking movement, artfully designed by millions of years of evolution to coax him to run with her on those golden fields, to join her in orgasmic bliss and flood her with the rich, life-creating semen that her estrus demanded she acquire.

Her contractions spilled all the way to her strained lips, sending that stretched crescent of clitoral flesh shooting even further from its now well-exposed home. A massive gush of steaming filly-nectar spilled out from the clinched junction of pussy and cock, the nearly impervious seal sending the spray farther and harder, like holding a hoof over the edge of a garden hose. Hot lubricating honey shot down his shaft and splattered against his swinging ball-sack and rear legs — inviting him to release his own orgasmic flow, to pay her an equal measure of climactic payload.

But Caisson wasn’t even close yet.

His filly would have to endure. More sensation. More bucking. More cock.

Still, his mind was flooded by that deep hind-brain with positive reinforcement and another flood of androgen and magic-infused rut-hormones. A true stud satisfied all the brood mares of his harem — and feeling one of them cream herself was a sure indicator that he was the alpha-stud… and that her body wanted his foal, was ready for it. The surge of neurochemicals sparked through his chaotic mind, made even more potent by the natural earth-pony magic that made the race such prolific reproducers.

He thrust harder.

Deeper and deeper, through his little sister’s half-screaming, half-moaning, hip-shaking orgasm, pushing his pink horsecock into her tiny body. The girth of the shaft entering Cookie’s was now as wide as his flare had been, and only getting wider. He could only make progress as she relaxed during one of the tonic-clonic orgasmic convulsions that were still wracking her body underneath him…

But then she bumped up against his medial ring… and all progress stopped.

Three-quarters of the way down his shaft, just before the eighteen-inch mark, a thick band of throbbing flesh demarcated the difference between the terrifying size of his upper stallionhood… and the ridiculous expectations of his cock base.

Just like a massive redwood tree in the Everfree forest... supporting a huge, long structure meant that an expansive, girthy trunk was a necessity. The immense foundation was as thick as a mare’s leg. Caisson was as wide around at his enormous base as his cock was long — a mare looking to take his massive size ought to practice slotting a dinner-plate into herself first.

Just the medial ring was too much for Cookie: a mechanical stop on the flesh-column rearranging her insides. As the big ring ground against the teen’s tight snatch, pressing her forward, a deep, desperate moan rumbled out of the thrashing filly underneath him.

“Ohhhhnnngh…”

Caisson huffed, stamping hard into the haybale underneath his hoof in sheer frustration. He was not satisfied with this limit — his rut demanded that he overcome every obstacle, surmount the impossible, and completely stuff his brood-filly. But there was no more force that he could apply; already his powerful hind-legs were screaming with lactic acid, straining past the point at which injuries, strains and sprains could occur.

If pure, unending force wouldn’t work… then it would need to be a jerking thrust.

For the first time, Caisson began to pull backwards. Shifting his weight from his hinds to his forelegs, pushing back against the bales he and his sister were propped upon and achingly starting his withdrawal.

“Gaahhnnn, C-caiss!” Cookie’s whimpering shudder was a mixture of relief from the pressure, petulant disappointment at the removal of the cock she had desired so badly, and new pleasure as the huge flare began to plumb her depths, grinding against her twisting inner folds from a new direction.

As he slowly withdrew, his little sister’s pussy came with him — the filly-hood lips gripping and suckling as inch by inch his slid back out of her, dragging those dark and pink labia and her stretched clitoris as he went. The massive bulge in his little sister’s belly was slowly retreating as Caisson’s fat horsecock slipped out of her with a sucking, squelching sound from the immense suction of so much meat being displaced.

“CAISSON!” Cookie yelped in warning, as she had to grip the band of the haybale to prevent her whole body from being pulled backward, as if her teen-fillyhood was trailer hitch attaching her to a hydraulic hoist. Only because she was holding on with all her strength was he able to continue his slow, deliberate back-stroke.

But he wasn’t pulling all the way out.

Just enough to reset his purchase, to give his body enough leverage and run up to give a violent, sharp, bucking — THRUST!

With a mighty lunge and snort of air, he drove forward. The eight inches of slick, pink cockshaft he had just withdrawn plunged back into his little filly with knee-weakening force..

“GAH!” Cookie squeaked, as she was slammed back forward into the edge of the haybale.

The whole pyramid of stacked hay cubes jumped, shaking more violently than if Ponyville had received an earthquake: some of the top bales came crashing down tumbling and rolling off like straw-colored boulders, bursting into explosions of hay. Only by Celestia’s grace were neither of the incestuous siblings crushed by the heavy bales as they crashed all around them.

*POP*

But it worked.

Caisson’s girthy medial ring popped into Cookie’s tight teenage pussy, quickly introducing her body to the unbelievable girth of her older brother’s lower cock-base. Only some quirk of earth-pony reproduction magic could have permitted the impossible stretching needed as she sank lower onto the veined, pulsing base.

“Ahn! AhhN! AHN!” Cookie moaned out in little furtive clenches. Caisson could feel his little sister’s pert, athletic flanks pressing into the sides of his stallionhood’s base now: his girth was so wide that even her butt-cheeks were being touched by his impressive width.

Caisson felt a thump against the end of his flare — like he had slammed into an elastic, stretchy wall. There was no more depth for him to push into. He had reached his little sister’s womb, his huge knobby flare pounding against the gate to her deepest feminine core, smashing against the clenched portal of her cervix.

“Oh! OHHHH!” According to legends passed around the cafeteria table, some mares loved cervical contact, others didn’t. Judging by his little sister’s milking, climaxing clenches as he pressed against her deepest sexual gate, she was one of the former. “BC! BC!”

Splatters of filly-juice soaked down his tree-trunk base, gushing out with each new clenching spasm, running down his cock and waterfalling off of his low-hanging testicles in a waterfall of erotic lubrication.

Whinny!

A triumphal roar that would make even the fiercest of ancient, primordial horse-studs shiver in fear bellowed out from Caisson’s chest, as he straightened up and flexed his muscles in arrogant victory. I’ve stuffed my little brood filly!

The motion lifted his little sister up as his flexing cock rose up to his belly. Cookie’s hooves came up off the barn floor and the haybale — suspending her entirely in the air. She was being entirely lifted by his stallioncock.

Cookie was suspended in mid-air, hoisted up by Caisson’s massive stallionhood.

“Ahhh!” the filly’s hooves pawed and paddled at the air, making her look like some bedraggled puppy being held over a bath.

Caisson turned slightly, as he considered whether to take his new broodfilly prize to somewhere more convenient to rut her… swinging her underneath him while she was fully lifted by the sheer power of his stallionliness and the rigidity of his cock as she rode his belly. A few clopping steps brought her over to a nearby interior wall, used to separate off the part of the barn used for tools and storage from the side used every day — it was perfect.

He drove forward, finally allowing his sister to brace against the wall with her forelegs as he lifted himself up to a standing position himself, his huge forehooves reaching much, much higher on the cedar-planks. They were both standing on their back hooves now, in a perfect position for him to really start to buck.

“Ahn! AHN!” Her first moans came as Caisson started to pivot his hips, sliding an inch back and forth into her body, grinding against every nerve in her completely-stuffed pussy and bumping over and over into her cervix as he did so.

It was a slow rhythm, his balls softly swinging back and forth, and Cookie moaning and clenching, getting used to the powerful but laconic pace as he began to pump in and out of her, each stroke inducing a groaning exclamation. Manageable by the brave little filly...

At first.

He began taking bigger outstrokes, pulling further and further back with each piston, using his rump and legs now instead of just the tilt of his hips. First two inches of his bright-pink steaming cock slid in and out of Cookie’s dark lips, then three, then four.

“Ahn!”

*PLAP*

“AHN!”

*PLAP*

A new sound was filling the air — the muffled impact of his heavy stallion-sack swinging back and hitting the inside of his own legs as his increasing momentum started to cause them to
move through the air like a pair of shotputs hanging in a leather bag off a pendulum.
*PLAP*

“AHN!”

*PLAP*

Harder and harder, faster and faster. Each time battering his throbbing cockhead against the deep, unyielding barrier of her cervix. Their flesh was melting together now — those subtle, swirling folds of her fillyhood and the pulsating veins of his stallionhood. It was like they were becoming one body, their cacophony of wild motions and clenches and violent love-making forming some singular lust-depraved creature.

*PLAP* *PLAP* *PLAP*

“BC!”

His thumping, pounding rhythm was faster now, each thrust bumping his sister’s head against the wall, making it sound like somepony was knocking insistently on a door.

He could feel her orgasms as they came in waves, their flesh-union making it feel almost as if they were his own. Milking convulsions of her vaginal muscles and humping flexes of her body rippling through him, as his inner-thighs were whisked with her thrashing tail… before being coated with squirt after squirt of her sticky filly-spray.

His stud-brain was still in full control, running its primitive calculations. It judged his choice of mate positively: his brood-filly was a tough, courageous one. A worthy mother for his genes. She was thrusting back into his cock now, pushing backward with her hips to take as much of his monstrous masculinity that she could.

*PLAP* *PLAP* *PLAP*

“Yes! YES!”

He could feel the hard press of the wooden wall against his stallionhood through his sister’s body — her belly bulged from his penetration grinding against those planks as his rough force sandwiched her. She was literally entirely stuffed with HIM, his lusts, his desires, his overflowing rut… his cock.

She was giving her all.

And he still wanted more. Needed more.

He could feel the spring in his belly winding, metal under tension that hummed with built up potential energy, ready to snap and explode. His orgasm was close, a thick voluminous genetic payload that would forever claim the destiny of his brood-filly and secure their progeny. But his wild, ancient instincts demanded that he deliver his essence as deep and effectively as possible — he needed to empty himself into his filly’s womb.

*PLAP* *PLAP* *PLAP* *PLAP*

Harder! HARDER!

His muscles surged forward, pounding his little sister into the wall with the force of a hoofball linebacker, making the planks groan and shudder. Great, steaming gouts of fillycum and other obscene fluids splashed backward, extracted by the piston-like action of his plunging stallionhood, and still he slammed against the impossible barrier of Cookie’s cervix.

*PLAP* *PLAP* *PLAP* *PLAP*

WHY WON’T SHE LET ME IN?

Caisson started to bend his gasping, drooling mouth down toward his little sister’s lashing neck. A spot just before her wildly flowing mane looked particularly vulnerable, a soft nape of skin that might just be the final additional bit of leverage that he needed to ram himself into his territory.

As his teeth dug into her soft fur, he could taste the sweaty froth building up there, the salty exertion of his filly’s body the coating sheen of her exhaustion matching his own in their frenzied, pounding rut.

“OHHHH, CASE!” This was a feral growl, like some giant jungle predator, barked out with the volume of a scream but the baritone of a rumbling moan. Cookie’s head twisted to look at him. Her wide-eyes were filled with passion and fear, excitement and adrenaline. She was smiling with the dopey grin of a stumbling Berry Punch, even as her own teeth snapped dangerously at him.

They weren’t brother and sister, crossing a forbidden taboo-line to fuck each other lovingly in their family barn.

They were two young horses, earth-ponies in complete rut and estrous, having entirely succumbed to the wild, primeval neural pathways and thaumic forces that evolution had left in their modern pony-bodies.

*PLAP* *PLAP* *PLAP* *PLAP*

Cookie’s gnashing teeth and head were quickly followed by a small bucking kick… which made Caisson’s rear hooves slip as they took on all of his sister’s weight at an awkward moment in one of his plunging strokes.

Suddenly, the barn wall was bearing all of their weight at the precise moment that Caisson’s heaviest thrust slammed into his little sister’s hips. A rending crack joined the wet slapping sounds filling the barn as the cedar planking of the wall groaned and bent — before snapping in two.

*WHAM* *CRACK*

Caisson had just fucked his sister through the wall.

After the one plank broke, they all began to fail, one after another in a huge, chaotic collapse. Timber, nails, hay, and ponies came crashing down onto the other side of the interior wall. Cookie’s body came tumbling under her big brother’s, who managed to ride the small-scale building demolition down, landing on all four hooves right on top of his sister. The smaller filly had slammed bodily onto her chest, front legs splayed out in front of her and her head against the ground.

Her rear end was still suspended in the air by her stud’s rigid, throbbing-pink penis — leaving her face-down, ass-up in a position that allowed her big stallion to bring all of his force to bear against that final stronghold.

That final, pistoning thrust that had rent the very structure of the barn continued on through the fall… bringing the full force of all that horse-muscles plus the momentum of its weight bearing down in one, ultimate movement.

*SPLAP*

Caisson’s huge testicles swung forward at the same time, slamming into Cookie’s teats and sending out a spray of filly-nectar from the coating that had slicked its surface.

“CASE!!! AHHNNNnnnNNNNNgh!” Cookie’s orgasmic growl reached a new crescendo, more like a screaming squee. She turned her bright blue eyes up to look into his. Those beautiful irises shifted, morphing... quickly forming into a pair of heart-shaped irises that throbbed and pulsed with intensity.

He could see at that moment, his little sister’s complete and total transformation. Her mind, her heart, her spirit… they belonged entirely to him and his masculine studliness now. This was truly his special talent — he was an alpha. And his sister was the first to fall entirely to him.

Deep inside her body, he felt his huge, throbbing flare press into that impossible opening. Only some divine intervention of the Princesses, or more likely some lingering earth-pony magic ability would have ever permitted his gigantic girth to penetrate her cervix and enter her womb.

And yet it did.

Caisson’s throbbing flare slipped into that final bastion of his little sister’s deepest, most feminine refuge, the life-creating factory so sacred and wondrous and feminine.

“...HnnNnh*GAH*ghhHHHH!”

And it slammed against the far end of it, driving a bulge into Cookie’s diaphragm that interrupted her moan with a hiccup like gulp.

Caisson’s perception was razor-sharp, his mind drinking in the details of every nerve fiber even as it overloaded his cortical circuitry. Cookie’s whole body was in a state of ur-orgasm. Her heart-eyes danced and dipped wildly, an indication of the wild wash of endorphins, neurochemistry and magic melting her pleasure centres. Her whole buddy pumped and gyrated up against her brother, trying desperately to stuff the final few inches of his cock into her body and hilt him, despite the fact her body had literally no more ground to give.

Each gyration was in perfect synchronization with the involuntary, milking clenches of her whole vaginal tunnel. Every muscle in her body was cooperating to create powerful, suckling grasps of those vaginal walls… heavy strokes that would have put a seasoned milkmare to shame.

He trembled as her womb expanded and thrummed, preparing to receive the estrous-sating load it had been so desperately demanding for so long.

He could sense that the whole of her mind, body, and soul was begging for her brother to join her in the forbidden, terrible consequence of culmination.

Everything in her wanted him to cum.

Fill her.

BREED HER.

And he did.

The pulse of pleasure was sudden, like a gunshot. For a moment Caisson wondered if he had been struck by lightning, or if some tendon or muscles had torn in the fall. The surge of pure testosterone raced from his hind-brain, washing down through every one of his arteries and veins, igniting every nerve filament on its way; a branching bolt of overwhelming sensation that accompanied the instruction from brain to balls to fire.

His balls shot upward, the clenching muscles of his powerful abdomen pulling them in tight as they swelled with a rush of magical energy.

His flare, already fully-expanded, managed somehow to grow even wider. The blossoming plate of stud-flesh thickened, the knobby bumps in its edges embedding themselves into Cookie’s womb-walls, firmly lodging the hoof-sized hunk of flesh in place.

A throb of swelling flesh raced down his length, like a cartoon-hose bulging after being connected to a fire hydrant.

His urethra thickened to the half the size of a bit, opening wide from the pressure of the release, screaming up his shaft.

And then he exploded.

The first blast of boiling, fertile stallion-batter shot with enough force that any pony watching would have seen a bump appear on Cookie’s underbelly. Heavy, glue-thick cream splattered and swirled out of him, an unending, unremitting flow that lasted for seconds.

*PLAP* *PLAP*

“YesSss… YesSSsShhh!” Cookie’s moanings were made nearly incoherent by her hanging tongue, and the sound of soft thuds of her flanks against his cock as she humped back onto his rigid, jerking stallionhood. She was impaling herself onto his orgasming penis, delirious with the joy of the heat-sating potion gushing into her.

Within the first few seconds, his gushing stud-cum had filled his little sister’s womb — the boiling body heat of her internal body temperature keeping the creamy slurry a frothing liquid as it topped off her uterus — then began to expand it.

*PLAP* *PLAP*

“Unhhh…….”

The second blast followed right after the first. Heavy wracking spasms of stallion muscle that squeezed with coordinated force to wring out every drop of semen, each one swimming with life-creating sperm. The little filly’s womb was getting packed — the seal of her stud’s flared head inside her plugging any possibility for escape, causing the pressure of the hot, frothing cum reservoir inside her to rise.

*PLAP* *PLAP*

A third shot. Then a fourth.

Each one seemed to last just as long as the one before it. Impossible amounts of stud-essence were being generated and injected into his sister. Only some arcane combination of special-talent, genetic lottery, and earth-ponic magic could be responsible — already Caisson had produced a milk-bottle’s worth of volume without any hint of tapering.

*PLAP* *PLAP*

“G-Guh… Goddesses!” Cookie squeaked out, still clenching and climaxing around her big brother’s orgasming cock, “It’s… too much!”

Caisson could hear her, but it didn’t mean anything to him. He had been flooded with so much oxytocin and dopamine that even his instinctive drives had begun to burn out. Everything was just pure, searing pleasure now.

He felt like he had merged, melted into his filly, becoming a single organism.

There was no ‘Caisson’ anymore. Just flesh and feeling… a grunting, heaving sensation of emptying.

*PLAP* *PLAP*

As his sixth blast stuffed the overly packed filly, her belly began to expand outward. Subtly at first, a barely noticeable bump in her abdomen — but now that her body had begun to stretch, it came faster and faster… like a water balloon held under the sink faucet.

*PLAP*

“Ahhnn… ahnnn!” Cookie’s moans were coming with each orgasmic burst from his still-emptying balls now. The blasts slowing in frequency but not intensity, and each one growing the once-small taupe lower belly larger and larger.

Already it looked like the teen was four months with foal as her cum-belly began to push against the tops of her teats.

*PLAP*

Slowly, dimly… Caisson’s mind was coming back. He was ascending from the depths of the little-death toward the light of consciousness. The dark edges of his vision swam with photopsia-flashes as his brain began to reboot, pathway by pathway.

*PLAP*

“Mmmnh! Mmh…” Cookie’s belly was obscene now — nearly touching the barn floor, and pressing up against her lower ribs, as her womb accommodated the tenth blast of piping hot cum from her stud’s ridiculously potent reproductive system. If Nurse Redheart had a look at her she would have prepped a midwife for an immediate delivery… this filly was eleven-months pregnant, possibly with twins.

*PLAP*

“Cuh… C-Cookie?” Caisson groaned, his head throbbing.

Where was he? What was he doing?

He felt another incredible release from his cock, which felt so painfully full and yet so wonderfully gripped, in something so massaging and tight and…

Oh Goddesses, he was cumming inside his little sister!

He felt his stomach drop out from him, a sudden surge of guilt, panic and terror.

What had he done!? How was this happening?

Instinctively, he began to jerk back, only to find that he was lodged inside his little sister. He’d never felt so huge, so engorged, before… there was no way to back out of this. He felt a strange mixture of release and shame as another shot raced out of him, knowing that it was stuffing his little sister’s body, that he was creaming her.

*PLAP*

And she was humping into him!

“C-caisson… I…” Cookie groaned out, looking up at him with heart-shaped pupils. Her mane was bedraggled, drenched with sweat and other fluids, little twitches in exhausted muscles making her quiver and whimper. She’d given it her all. “I… love you, big bro.”

Caisson felt his heart melt. That was his little sister.

His precious little sister.

She loved him! And dammit if he didn’t love her too. Not just some pleasure-mare, some buck-buddy or a worthy target of an accidental rut: his sister.

The initial wave of guilt began to slide away, replaced again by the wash of post-orgasmic chemistry that could bind two hearts so closely together after the tumultuous chaos of sex.

He would be there for her, always. And that meant now, too.

*PLAP*

This time it was Caisson pressing down into her, a gentle, soft thrust meant for her. Not him.

“Shh…” Caisson cooed, carefully lifting a hoof to stroke his sister’s mane. “I love you too, sis.”

*PLAP*

“Mmmm…” A contented sigh-giggle escaped from Cookie as her loving big-brother loosed his final cumshot into her body.

*POP*

Her belly-button popped outward, turning from an innie to an outtie, her cum-stuffed tummy rumbling with contentment.

“C-case…please...” She whined, blinking up at him, dipping her eyes and pursing her lips. The tone reminded him of when she would beg for ice cream as a foal.

“It’s all gonna be OK, Cookie.” Caisson smiled, leaning in and planting a kiss on her lips. He didn’t know how to kiss, this was his first. He’d kinda put the cart before the pony there. There would be no Prench-kissing, no slobbering and necking. The peck of his lips on hers, brother to sister, pure love… was more than enough.

Her tense, spasming fillyhood, exhausted… finally seemed to relax. Both of them were coming in for a soft landing after what felt like an eternity of strenuous hyper-stimulated climax.

*SCHLORP*

“Ahn!”

A combination of Cookie’s relaxing filly-muscles and Caisson’s ever-so-slightly softening stallionhood was just enough to create the tiniest of gaps breaking the seal of flare to uterus. With the force of the emergency spillway of Ponyville dam being opened, a huge waterfall of burbling, thick, glue-like cream began to squirt from the tight junction of Cookie’s outer lips and Caisson’s still-girthy base.

“Shh… shh…” Caisson whispered, stroking his sister’s mane and resuming their gentle kiss.

*SCHPLAP* *SCHPLAP*

Caisson moved his hips gently, slowly. The wet, soaking sound of his humps mingling with the content hum of their smouldering kiss.

“Mmmmnnn… big bro…”

“Cookie…”

*SCHPLAP*

Carefully, Caisson rolled off his aching legs onto his side. He was still embedded deep within his little sister’s belly. Though it wasn’t quite as plump as it had been before, she was still looking quite pudgy as they both lay side by side in the growing puddle of his out-spilling semen amidst the wreckage of their earlier wall-breaking union.

*SCHPLAP*

They were comfortable now, spooning each other, and slowly, gently bucking. Soft, tiny strokes accompanied by the wet schlorps of his fertile batter being plumbed from her. There wasn’t the insane, heightened passion-inferno of before, but their happy, slow-fuck burned just as hot. They stared into each other’s eyes, content to live in just the moment.

Perfect.

It was perfect.

Caisson could have lived there forever, with Cookie. What else mattered than this feeling? Of loving and being-loved so completely? Did the outside world even ex-

...

“MOOOOOOOOM! CAISSON AND COOKIE ARE FUCKING IN THE BARN!”

Caisson watched as Cookie’s eyes shot wide in fright and alarm, like she’d been doused with a bucket of cold water.

Posey.

Their baby sister.

Standing in the open barn door, from where she could see everything and calling back over her shoulder. She must have just arrived from grade-school! Their mother would be meeting her to harness the blank-flank filly up!

“P-posey, you little ratfink, shut up!” Cookie half-squeaked, half-screamed. She surged, trying to stand up, only to find Caisson’s still-embedded stallionhood preventing her.

“Posey, language.” Golden Harvest’s voice drifted through the door, getting closer.

“It’s TRUE, Mom. And they even BROKE A WALL. You guys are in big trouble, now!”

Caisson watched, terrified, his hooves unable to move as his mother appeared in the doorway. There was no chance to hide, no way to explain the fact his mammoth, big-pink-cock was embedded in his little-sister’s cum-fattened belly.

All he could do was pray to Celestia.

“What are you going on about young filly? Oh. Oh!” Golden Harvest looked at her two eldest children.

“H-hey momma…”

It was a cold, mid-March day. The day after Winter-Wrap up.

A Sunday.

And Caisson’s least favorite day of the year.

Today was the day that field-work started, all over again. With the guarantee of no new snowfalls from the pegasi weather-teams, it meant that the family fields could be cleared of snow) and readied for the spring season.

It was dark. It was wet. It was cold.

And he had a long day of work ahead.

At least, he comforted himself, it would be easier than the previous year. He was bigger, stronger, more experienced. He’d already felt it when moving Ponyville’s biggest plow the day prior. He’d grown even more since the fall, just as his mother had expected, finally reaching his full size by Hearth’s Warming Eve.

The biggest farm-stallion in Ponyville’s whole history, they said. Records in both height and weight and power.

Pride of the town.

It actually hadn’t bothered him as much as he’d once worried that it might. He’d found a new self-confidence in the fall semester at Ponyville High, and quickly he’d realised that he’d been misreading a lot of the signals over the years.

Turns out, those frou-frou fashion magazines with idealized slender pegasus-colts and dainty unicorn-stallions were a far cry from what the mares and fillies of Ponyville actually found attractive.

Once he’d started understanding what those signals from fillies his age — and quite a few mares around town — actually meant, well…

He’d actually been called in by Principal Cheerilee at one point to be careful about sowing wild oats too prolifically around town. He’d gotten a long lecture on the use of contraceptives from the pink-haired instructor if he was going to continue indulging what was clearly his ‘special talent’, particularly as they headed into a new heat season.

‘It won’t be good for the town’s genetic diversity to have a whole high-school of fillies heavy with Little-Caissons running about. I’ve talked with Mayor Mare, and we’d both like you to restrain yourself when it comes to the townfillies.’ Caisson had blushed extremely, profusely apologizing that his activities of the past few months had become so legendary... and assuring Principal Cheerilee that he would always use protection with his partners, and reduce the frequency of such events. Thoroughly scolded, he’d turned to leave her office, only to suddenly feel a tug on his tail.

‘Hang on now. I just mentioned townsfillies. Lonely, single, foal-less mares on the other hoof… both I and Mayor Mare want to be clear that un-married mares are very much fair game. I think she’ll be wanting to see you this afternoon about getting a Little-Caisson of her own. But she’ll have to wait her turn, you have a free period right now, don’t you?’

He chuckled to himself, remembering that particular afternoon.

A bright memory before a long, dark day.

He groaned as he picked up his harness. Still the same old adjustable mess of buckles and straps that he’d known for the past few years.

“Sheesh Mom, didn’t you say when I was done growing we could get me something custom-fit?” He griped, looking over at his mother, who was being strapped in by Posey. It was the morning, so the whole family was in the barn at the same time, enjoying the last bit of warmth before they would have to head out into the dark, cold spring morn.

Golden Harvest shot him a look, the look that only mothers can give.

“Well, son of mine. I did budget to get you a lovely custom-fit harness, and it would have made oh-so-nice a Hearth's Warming Eve present for you.” She snarked, clearly also grumpy at the work ahead. “But, all of a sudden, out-of-the-blue… I had to spend those bits on a specialized rig for pregnant mares! I wonder why that is?” She tapped her hoof sarcastically against her chin, as if pondering. “Maybe you can figure that mystery out while doing the whole South field with your sister today?”

“Hah!” Posey giggled, shaking her head annoyingly. “You tell ‘em, Mom!”

“Posey, quiet.”

“The whole South field? That’s not f- OOF!” Caisson yelped, as Cookie buckled his belly strap in a single jerk, nearly driving the air out of his lungs. He turned to yelp at her. “H-hey!”

“Serves you right, you should have known Mom wouldn’t let you give her guff. Now shut up before she makes us do more.” A very pregnant, six-months-with-foal, Cookie harrumphed. “I swear if your foal is as much a blockhead as you are…”

“S-sorry.” Caisson folded his ears back, shrinking. He could never stand up to his beloved Cookie.

“Hmmf.”

“It’s my fault, really.” Golden Harvest sighed, repeating what she had a million times before over the past few months. “I figured you two would romp in the hay a few times, but never thought about Cookie’s late heat. I really should have: I nearly had the same thing happen to me with your uncle, Carrot Cake, you know… quite a scare but in the end a false pregnancy.”

“So you always say, Mom…” Cookie sighed, the same tired response to the same story.

Caisson knew well enough to keep his muzzle shut — The truth was, he didn’t mind having Cookie have to ‘adjust his harness’ every afternoon.

The end.