Bulge

by Megapone

Rating: mature
Tags: Romance
Length: 7472

Twilight likes having a "big" big brother. She wants to make sure he stays that way.

Twilight likes having a "big" big brother. She wants to make sure he stays that way.

Contains: Crotch Bulges, Cock/Ball Growth, Incest, Deepthroating, Cum Inflation, Large Insertions, and Stomach Bulges

Published 1970-01-01 00:00:00 UTC
Last updated 2015-07-09 01:22:20 UTC

The Visit

Knock knock.

Shining Armor didn’t even look up from his comic. “Come in!”

His door creaked open. Shining’s ears twitched at the sound of a familiar, “Hello…”

He glanced up over his current page. Instantly, there was a red tinge on his cheeks. Twilight stood in the doorway, appearing, to all the world, to be the angelic little sister that the whole family knew her to be. Yet one detail was off—her eyes, usually bright and innocent, were half-lidded, perfectly framing the sly smirk that had crept its way onto her face.

“Oh!” Shining scrambled to set his comic aside. It slid onto his night-table, forgotten. “Twily! Right!” Oh, who was he kidding; he’d known she’d be coming.

She laughed. “Good to see you too, BBBFF.” She trotted into his room and swung the door shut behind her. Shining could barely keep his eyes off of her swaying hips, her round, curved flank—

He snapped himself back to reality. Twilight was looking at one of his posters, the Sky-High Fliers one. “That one new?”

“Uh,” he said. “Don’t think so.”

“Huh,” she said. She turned to him. She was smiling from ear to ear. There was something almost...unnerving about that smile. A wiser stallion might have paused.

But to hay with that. Shining grinned awkwardly back. “Mom and Dad?”

“Out to dinner.” Twilight checked the clock above his bed. “Won’t be back for a good...two hours.”

Shining’s whole body relaxed. He slowly exhaled, releasing a breath he hadn’t known he’d been holding. “Good,” he said. He was almost surprised when he realized that he meant it. Could he really have been looking forward to this this much?

He looked up and met Twilight’s eyes. They glittered in response, mischief darting about in deep-violet irises. Damn him, but he had. He licked his lips again, swallowed.

“Good,” he said again.

Twilight hopped onto the bed beside him. She grinned, laid a hoof the inside of his back leg. “You even dressed up for me!” Her voice squeaked, for an instant sounding like the adorable little sister he’d always had. Then he saw where her gaze was pointed, and his heart sank—but something else rose.

“Uh,” he said again. He blushed even harder. “Yeah. I guess I did.”

Twilight bit her lip, met his eyes. “Can I…?” He nodded.

She giggled to herself as her hoof made gentle strokes down his thighs, slowly but surely getting closer to the space in between. Her hoof brushed against his crotch and he gasped.

Twilight giggled again. “You’re excited, Shiny.”

Shining grinned, helplessly. “That obvious, huh?”

Twilight nuzzled her brother’s crotch. “Mm. I really love the smell.”

Shining bit his lip. His hooves dug into the bed and clenched the sheets tight. Suddenly, he was getting second thoughts. “Ungh. Twilight? You sure...we should...ungh.”

She ignored him, of course. The funny thing was, he wasn’t even nude. Of course, ponies were usually nude anyway, but he’d snagged a pair of briefs earlier in the evening. Whether they were there to conceal or to emphasize, though, was up for grabs. Since he’d known Twilight would be coming that night, it wasn’t difficult to guess which.

Her muzzle prodded again at his groin. Shining groaned as her mane brushed against his thighs. Another stallion, perhaps, would have succeeded in hiding his package beneath the clean white fabric. But for a stallion of his size, the exact opposite was true.

With a shaft that was seven inches long soft, and a pair of balls each three inches across, the pair of briefs did little more than accentuate his already impressive size. His balls bulged impressively against the fabric, while his flaccid dick curled up into a thick bulge of its own a bit further up his crotch.

Shining moaned softly as Twilight nuzzled deeper into his crotch. His own musk reached him, causing his nostrils to flare. It was a rich, deep scent, and he felt his dick twitch at the smell.

Then he imagined their parents coming back home early. Surprising them. Catching them in the act. The shouting, the anger, the punishments—

“Not tonight, Twily,” he muttered. He made a halfhearted attempt to push her off. “I’m tired.”

Predictably, she didn’t listen. “You know,” she said, laying her head across his thigh. “I was thinking about you today.” Oh, boy. “And then I came in here and found you all dressed up for me.”

“It wasn’t—” he began. The words melted from his mouth as she slowly drew her tongue across the inside of his thigh, her eyes half-lidded.

Twilight giggled. “See,” she said, her hoof tracing small circles over his package, “I really like seeing you in these. Makes me realize just how big you are.” She shuddered happily; Shining could swear that he saw her thighs clench as she tasted the word. “Makes me realize how lucky I am to have you for a BBBFF.

“But,” she said. She gave one of his fat, bulging orbs a gentle squeeze. He gasped lightly, his lips forming the shape of an “o”. His dick just twitched again, this time even harder. “That just made me think about how much better you’d look bigger.”

“Uh.” Shining swallowed. He could feel his dick getting harder already. He was suddenly extremely aware of the seed weighing down his balls, and of the tightness of the briefs around his crotch. His dick gave another twitch. Glancing down, he could see it already poking up against the left leg-hole of his underwear, its thick head an obvious, even obscene bulge against the fabric.

His right leg twitched. Biting his lip, he noticed that there was a damp spot spreading across his underwear. He glanced back up and met Twily’s eyes. What he saw there did not encourage him.

“Twi,” he said. The tip of her horn was flickering purple. “What—nggh—are you doing?”

Her smile was absolutely angelic. “Making sure my Big Brother Best Fuckbuddy Forever stays big,” she said. With that, she planted a kiss on the top of his bulging briefs—and released the spell.

Shining groaned as the magic went to work. He could feel it in his loins: a warm, tugging feeling that filled his entire crotch. “Twily,” he said. He was about to say ‘no,’ but an overpowering sensation of tightness soon overwhelmed him.

Out of the corner of his eye, he could see the bulge in his briefs swelling, growing larger and larger by the second. His eyes widened slightly. His cock was now fully erect: eleven inches of thick stallion meat, straining against the fabric of his underwear as hard as it could. The damp spot just kept growing, easily doubling in area as the steady flow of pre from his tip only increased.

But as he watched, shock evident in his eyes, his boner got even bigger. He watched it swell, thickening until it was nearly half as wide as his hoof. On and on it grew, passing a foot in length—no, fourteen inches, now—until it was clear that the underwear could take no more.

With a rush of cool air and an overpowering sense of relief, Shining’s cock pushed free of its tight, musky prison and slid down his leg like a long, hard snake. Sixteen inches. Seventeen. It finally tapered off at an incredible nineteen inches, a shaft so huge that most stallions could only dream of its length.

He winced and let out a grunt. Another glance at his crotch gave him the answer why. His balls had swelled up to the size of oranges, and were straining against the briefs even more powerfully than his shaft had. He grit his teeth as they grew into veritable melons, their six-inch diameters bulging obscenely between his legs.

The underwear was so tight. His breath came in short, tight spurts as he struggled to keep himself together. He began to sweat. He could feel the cum sloshing in their depths, could feel those lakes of seed filling and swelling by the second. By now, the fabric had been stretched so thin that it just clung to his enormous package, every square inch of area outlined by a clean, glaring white.

And the weight. They were so heavy. So...big.

He met his sister’s eyes. Her smile spread ear to ear. He smiled back.

She laid a casual hoof on his bulge. Shining’s whole body stiffened, and his cock flared, spurting out a few thick ropes of cum without any further stimulation.

“So,” his little sister said, that angelic look on her face again. “Do you like it?”

The Release

Shining’s nostrils flared. Did he like it? He could feel his new monster of a cock throbbing against his leg, his blood pulsing inside of it like a second heartbeat. He could feel his new massive balls churning with seed, could feel them swelling up against the stretched fabric of his once-proud underwear.

He snorted, and his eyes squinted shut as a shudder of arousal went through him. Did he like it? Shining had always prided himself on his intelligence, and, ever since he’d started working toward making the Royal Guard, his physique. The sheer size of his member, though, drew him in like a black hole, devouring all other parts of him that might have mattered.

In that instant, that twenty-inch cock comprised the entirety of his being; his thick, musky scent filled his lungs to the brim; his melon-sized balls, squeezed so tight in the confines of his damp, thong-thin underwear, sloshed so thickly that they may as well have been wrecking balls shattering the barriers of his psyche.

He took a slow, deep breath. Then he glanced down at Twily. She had her chin resting on his thigh, her muzzle prodding gently against his massively overstuffed crotch. Did he like it? He nodded, at first hesitantly, then faster, almost joyfully.

A smile let up her face. “Good,” Twilight said. She laid a hoof on one of Shining’s balls—he groaned into his hooves at her touch; the underwear was so tight, his balls so full, his vast stores of spunk swelling larger and larger by the second—and massaged them gently. He moaned aloud this time, and his throbbing shaft spurted another generous dollop of cum onto his bed.

He needed to get those briefs off. Never in his life had he felt so large, so constrained in something so obviously small. But as a spark flickered on the tip of his horn, Twilight already had taken his massive bulge in her hooves and was nuzzling it gently.

“Mm,” she murmured. She took a deep whiff of his masculine scent, and her lower body trembled in delight. “I worked hard to make sure I got the spell right. I wanted it to be a birthday present, actually.”

His ears perked up. Wait. But his birthday had been two months ago. From the glum look in her eyes, she was thinking the same thing.

Twily sighed. She hefted his package from one hoof to another, no small feat considering that the whole thing must have weighed nearly twenty pounds at this point. Shining quietly wondered how he was planning on walking with that damn thing hanging from his crotch. Then again, Twilight had probably considered that too and prepared for it. Or else just didn’t care.

He shivered as he felt her warm breath on the bare skin of his nuts that had managed to squeeze through the confines of the fabric. His member seized up again, and his left leg was treated to another quick white bath as his oversensitive stallionhood continued even further into overdrive. “Unf. Ugh. Twily…”

“But it’s okay, because you still like it. Right?” She blinked up at him, biting her lower lip. She nearly looked like she’d turned in a homework assignment late, or as though she thought she’d failed a test. Privately, Shining reflected that it was pretty darn incredible that she was making that same look over a spell she’d used to grow his crotch.

Then again, this was Twilight Sparkle. If his little sister could find a way to turn sex into a test, she’d have a multiple-choice practice exam and a study guide prepped faster than you could say “study orgy.”

Shining gave an unsteady, shaky breath. “I...love it, Twily. Really,” he added, meeting her eyes. A warm smile spread across her face.

“Excellent,” she said. “I just wanted to make sure.”

He groaned under his breath as she nuzzled back into his crotch. "Twily," he grunted. "What're you..." He never got the chance to finish his sentence.

Twilight, one hoof still stroking the top of Shining's enlarged nutsack, opened her mouth slightly atop Shining's engorged member. It was still stuck in place, the rubber strip of his underwear cutting into the thick, meaty shaft and pinning it against the inside of his thigh. He moaned under his breath while she suckled on the space just beneath her flare: not sucking, not blowing, just tasting.

"Ooh." He twisted on the bedsheets, his hooves tightening. "That...wow."

Twi let his member pop out of her mouth with a wet-sounding pop. "Mm," she murmured, licking her lips. "Even better. I wonder..." She let her tongue dangle, and slowly lapped up the front side of his head. Shining groaned as she lapped eagerly at his oozing pre, grunted when she planted a light kiss on his cockslit. His cock gave another involuntary throb. When Twilight pulled away, the coat above her muzzle was drenched in another thick rope of his cum.

"Sorry," he mumbled. But Twilight was giggling. She reached up and played with the thick, creamy strands on the tip of her nose before levitating them away to the bathroom.

"Wow," she said. From the gleam in her eyes, Shining wasn't sure if she wanted to fuck him or study him. "And that's without any real stimulation?"

"Well," Shining said. He was gritting his teeth. "I'd say a pair of underpants tight enough to—ngh—cut off circulation in your lower body, along with—ungh—a package so heavy you feel stuck to the mattress—mmff—would do enough to stimulate anypony."

Twilight looked sheepish. "Ooh. Right! Forgot about that." She gave his stretched underpants another prod. "Though it's pretty darn hot seeing you like this, Shiny." She looked over his balls with wide, curious, analyzing eyes. "I wonder how much cum you have in these? It's obviously more than enough to drench the fabric three times over."

Shining grunted as his cock gave off another spurt of cum. By now, there was a puddle of pre and spooge mixing between his legs at least a foot across. That was going to stain for sure. The sheets felt heavy, damp with his seed, and his underwear, though still bulging obscenely, had all but become transparent when his first spurts of pre had finished spreading across it. By now, they served as little more than a cradle for his massive package. He groaned as Twilight prodded his balls again. He could feel the cum sloshing around inside.

Just by looking at the puddle on the bed, it'd be hard to believe he hadn't cum yet. But from the sheer volume he could still feel churning in his massive nuts...well. He was almost terrified to see how much spooge he still had inside them.

"Mm," he heard her murmur. Then, with a flash of her horn, the underpants were gone.

Shining sighed in relief. He flopped back onto the bed, and his near two-foot member sprung up into the air with him. It slapped against his belly, then bobbed back up above the rest of him. It almost looked a little ridiculous: that massive, twenty-inch shaft swaying innocently above a pony whose whole body couldn't have been much more than three times its size.

He felt so wonderful, so free. His balls churned and throbbed happily, not painfully, now that they were free of their fabric prison. His cock gave a small additional spurt of pre, which dribbled down his veined shaft to rest on his cantaloupe-sized balls. Shining just breathed in and out, his chest rising and falling as he just basked in his sudden looseness.

Twilight giggled. "Wow, Shiny," she said, hoof over her mouth. "Looks like you're happy they came off."

"You don't even know," he groaned. He swept one hoof onto his chest. The other went to his crotch, and began to stroke at the base of his shaft. It was almost a reverent, awe-filled motion. "Wow. This thing is just..."

"Big?" Twilight supplied helpfully. "Enormous? Massive?"

"All of the above," Shining said. He rolled his eyes. "And I'm sure you could come up with some better adjectives than that, you little bookworm."

"Ooh, ooh." Twilight sounded eager. "How about gargantuan? Titanic?"

"Better." Shining pulled himself back up into a sitting position; his erection slapped gently against the tip of his muzzle. "But I don't think it's that big." At the sudden hungry look on Twilight's face, he quickly added, "Not that it needs to be?"

"Aw," she said. "Oh, well." She grinned at him, then, without warning, wrapped one hoof around his girth. It barely even reached all the way around. "Let's see how you taste, BBBFF."

"Huh? What're you—" Shining cut himself off halfway through as Twilight brought her lips to rest atop his flared head. He groaned, shifting his weight slightly, as her muzzle opened wide—wider than he would have even thought possible—and took his cock inside. Another spurt of pre erupted from his tip, and Twi slurped it all up. She suckled on his tip for a moment more, her lips stretching around his three-inch girth, before finally pulling away. Her lips came away with another wet pop, and she licked his silvery pre off of them with a smile on her face.

"You taste good," she said, beaming. "Really good. How'd that feel?"

"Good," he said. He licked his lips. "Though, uh. A little bit of teeth."

She scowled. "Darn. Let me try again." And before he could react, she'd gone down on him a second time. He bit his lip when he felt his flare disappear into his sister's muzzle again, winced pleasurably as his head twitched inside of her.

"Mm." It wasn't like she could make any coherent speech with that monster sausage in her mouth, but to her credit, Twilight did try. She met his gaze and tried to nod approval, which, of course, only had the effect of bobbing her head up and down his first few inches of cock. Shining's cock flared and spurted again as she managed to take the whole head in: a good five inches of thick stallion meat that would have stretched anypony's mouth to the limit.

Twilight was actually surprisingly good at this. Shining's knees quivered as he felt her running her tongue up and down his shaft, her head still bobbing gently up and down the first quarter of his cock. Fuck. Quarter. He'd stretched her jaw incredibly wide, and she still could only take a fraction of his size. The thought was incredibly hot to him, and he found his hooves creeping toward the base of his tool. He tugged on the bottom of his shaft, his hooves closed tight around it, as his sister's lips smacked around the top third.

But Twilight was getting better. She let out a long, low groan, muffled by the meat in her mouth, as she took a risk and took an extra four inches of his cock into her throat. That got him excited. Shining felt his shoulders tensing, his hips flexing, as the tip of his stallionhood brushed against the back of his sister's throat. He felt the head of his cock twitch and flare inside of her mouth. Another spurt of precum gushed out down Twilight's throat, and she gulped it down eagerly.

Ten inches. She was taking ten inches of his monster cock down her throat. But for a filly like Twilight, "just half" might as well have been an F. She wasn't a mare to give up easily. So Shining just squeezed his eyes shut, his hooves still pumping around the base of his shaft (and struggling to reach all the way around, even with his much larger grip), and struggled to keep the tension in his balls from mounting even higher as she suddenly dived down an additional three inches—no, four! Her jaw actually creaked audibly as his shaft stretched her mouth impossibly wide, his monster of a tool larger than anything else she'd ever swallowed.

He saw her eyes narrow in determination, watched her glare at the base of his crotch like a test waiting to be beaten. She'd taken a full three-fourths of his stallionhood down her throat, but was that enough for Twilight Sparkle? He watched in an aroused, almost frenzied fascination as her throat actually bulged around his cock, her cheeks spreading wider and wider as his medial ring passed through them. Saliva dripped down his shaft, her lips moist around his tool as her tongue worked at it.

He gave a little pump of his hips, and almost choked as he felt another two inches slide down his sister's throat. Oh, fuck. Oh, fuck. They were almost there, his monstrous tool scraping against the bottom of her throat. He didn't even realize it at first, but he'd wrapped his hooves around her head, and was slowly, carefully, pushing her down even further. He was sweating, his whole upper body shaking as Twilight took more and more of him inside her mouth. Seventeen inches. Eighteen. Nineteen—

His breathing was ragged now; he was gasping for air, his face contorting as he struggled to comprehend what his sister was doing right now. Sure, she might not be bobbing her head anymore (he was amazed that she was even still getting air at this point), but the sensation of her lips around his shaft, the sight of her throat bulging around his huge, fat cock... He shuddered, the pressure in his balls mounting ever higher as he watched her lips approach the inevitable twentieth inch, pursed as they prepared to meet the very base of his shaft...

The instant her lips touched his crotch, Shining felt something pop in the back of his mind. It was though a valve had been released, a pipe burst, a dam broken through. He could hear his balls churning, could feel his whole groin rumbling while the pressure in his loins reached a peak—and exploded.

His hips jerked violently upward, pushing Twilight's muzzle up into the air. Her eyes widened, her jaw cracking slightly around his cock as it swelled in her mouth. Shining's cock was swelling, growing, bulging—though not, this time, from magic.

Shining groaned and bit down on his lower lips as his hips slammed against the mattress again and again. Barely a fraction of a second later, Twilight's eyes opened even wider—

—and a flood blasted down her throat.

She gurgled around his cock, her tongue swishing frantically as he pumped load after load of cum down her widened, eager throat. In a single spurt, Shining came twice as much as he ever had in a single orgasm before. The second spurt doubled that, and the third left his balls aching for further release.

Shining didn't realize it, but he was groaning, almost shouting in pleasure. He'd thrown his head back, his muscles flexing on and off with no predictable pattern as surges of electricity jolted through his body. His stallionhood swelled and burst and swelled again as more and more of his seed unloaded directly into his little sister's throat.

Twilight, for her part, was taking it like a pro. With eyes narrowed after the initial shock of Shining's first loads, she'd suckled even more tightly onto Shining's jerking cock and was now holding onto it for dear life. All two feet of her brother's shaft jerked and twitched inside of her, bulging out her cheeks and throat even more as he pumped incredible amounts of spooge directly into her belly.

Soon, it became clear that he'd cum so much that it was having an obvious physical effect on Twilight—or at least on her stomach. Twilight moaned around Shining's cock as she felt herself being filled with his seed. More and more cum flooded into her, filling her up until her stomach could take no more. But Shining's seed kept coming, his cantaloupe-sized balls more than happy to empty themselves inside of her. So much seed flooded into her that it was hard to believe that his nuts could even have contained it all, but it just kept coming.

Twilight pressed a hoof down onto her belly and felt it swelling beneath her touch. She groaned, Shining's head flaring against the bottom of her throat as it bulged even wider, preparing for the final release. It came soon enough. Twilight's eyes rolled up into her head as what felt like gallons of spooge began to flood inside of her. Her belly grew and grew until she looked like a heavily pregnant mare, and it depressed visibly under her tightening hoof. In what seemed like no time at all, it was drooping over her hips, swaying back and forth in time with Shining's jerking cock.

And then it was over. Twilight released Shining's shaft from her lips and all but fell backward onto the mattress. Her lips released his tool with a slick-sounding pop, and as she flopped onto the bed, a long rope of cum remained connecting her mouth to his tip. Her oversized belly flopped along with her, pinning her down as it sloshed with her older brother's seed. Twilight groaned again. There had to be at least a few gallons in there.

Shining’s cock gave one final throb. With a gasp, Shining fell back onto his pillows, breathing heavily.

Fuck.

The Filling

Twilight’s groan of pleasure was long, throaty, and thoroughly satisfied.

“Wow,” she said. She had one hoof on her overfilled, bulging belly and the other stretched out on the bed above her head. She held her tongue between her lips and sloshed her belly around a bit. “Just wow.”

Shining was still panting. The rush of orgasm had subsided to a dull roar in his ears, and for a moment, at least, he was able to seize control of his senses. Even with that, the ringing pleasure of his new equipment still threatened to bowl him over. He was happy enough to stay with his back against his pillows, his chest rising and falling steadily as he struggled to regain some amount of lucidity.

“How…” He swallowed, then reached out to run his hoof over one of his nuts. The oversized testicle throbbed in return. It was warm to the touch, and far too big for him to cover the entire thing with his hoof. A groan escaped his lips. He could actually feel it refilling with his seed, could feel it growing heavier by the second with new volumes of unspent cum. Though they had shrunk slightly after pumping so much of his load into Twilight, they were rapidly swelling again. He could even see the bed visibly depressing beneath their weight. He shuddered as a pulse of tentative pleasure swept through him.

Twilight grunted suddenly. Shining glanced over his package at her. At least now he could see the rest of her. His enormous shaft had gone at least slightly limp, and was now draped comfortably over his massive balls. His member had angled down over the top of his nuts, leaving his leg-thick head to brush against the bed. Meanwhile, Twilight was struggling to haul herself upright into a sitting position. Her overfull belly sloshed loudly, pinning her to the bed. A quick levitation spell helped her upright, and her cum-filled stomach flopped loudly into her lap.

“Whew,” Twilight panted. She shot him a wry smile. “Thank you.”

“Sure,” he said. He was still feeling more than a little bit winded, and even more lightheaded. Whether that was due to the incredible orgasm or the amount of blood now being redirected through his stallionhood, he wasn’t sure. He settled for both.

He shook his head. One of his hooves was still absently massaging his swollen, cum-laden orbs, while the other moved up to scratch at the back of his neck. “Well,” he said finally. “That was fun. Maybe we should think about shrinking this back down, though.” He gave Twilight’s stomach a pointed look.

Twilight’s jaw dropped. “You’re kidding, right?” She gritted her teeth, struggled to heft her body into a more comfortable position. “I thought you liked it!”

“I do!” he said. “It just seems a little bit unwieldy. I mean...look at these!” He waved a hoof over his groaning, churning orbs. “I just unloaded a ridiculous amount inside you, and they’re already filling up again! They look even bigger!”

Twilight licked her lips. “Well,” she said, looking contemplative, “that does mean you can go for a round two…”

Shining’s cock gave an appreciative throb at that. Shining grit his teeth as it began to stiffen again. Already, his head had lifted a good two inches off of the mattress, and his balls were feeling fuller than ever. “That’s not the point,” he said. “I can’t go to school like this. I can’t join the Royal Guard with...these! And if Mom and Dad see—”

“They don’t have to,” Twilight cut in. “I learned an invisibility spell last year, remember?”

Shining rubbed his forehead. “Yeah, but that doesn’t help if you’re not around.”

“And?” Suddenly, Twilight’s face held an expression of sly contemplation. “Just imagine it.”

“I’d rather not.”

“Come on,” she said, and pouted. “It’s so much fun, though.”

He sighed, then decided to humor it.

“Just imagine,” she said happily. “You’re walking through the hall, and everypony can see how big you are. Everypony can see your stallionhood bobbing beneath your chest, smacking against the insides of your legs—”

His real-life stallionhood was chubbing up even more. Without even thinking about it, Shining let one of his hooves drift down to a spot just below his medial ring. It massaged his shaft gently, working into the thick meat of his tool. It was already drooling pre, widening the already impressive lake of fluids gathered on the mattress.

“—with your big, full balls sloshing between your legs, so wide that you have to walk bowlegged, so full of musk that everypony in the entire building can smell your musk—”

He moaned under his breath as his cock lurched, shuddering with arousal. He could feel it swelling and hardening beneath his touch. He bit his lower lip and shivered as a thick glob of spooge spurted from his tip to join the growing puddle of his fluids. Twilight’s voice still filled his ears, her every word evincing another throb of his cock and, on every third word, another shuddering lurch and splatter of cum.

“—and everypony knowing that you’re that big, that you’re my big big brother, and that I’m the only mare who can even take half your girth—”

With a cry, Shining felt his whole stallionhood seize up. Now at full mast, it merely throbbed once before shooting a massive glob of spooge into the air. It splattered against the ceiling and stuck, save for a few thick ropes that were left hanging down toward them. Shining stared at his full erection, then blinked owlishly up at the mess it’d made above him.

“Huh.”

Twilight’s eyes glimmered predatorily. “So,” she said, almost innocently. “Would you still be against a second round?”

Fuck no.

He shook his head wildly. Twi grinned, fell back onto the bed. “Good. Then—”

But Shining had already shifted himself onto his knees, his massive erection bobbing in the air before him. He barely had to move at all before his member was poking against Twilight’s outer lips. Her mouth formed an “o” as he prodded against her labia—his shaft was easily as thick and nearly as long as one of her legs! And all that was going to go inside her?

But she didn’t even entertain those doubts for a second. “Well?” Twilight said. She raised an eyebrow. “What’re you waiting for, Shining? Your little sister’s ready for you.” She said the last bit in a high-pitched, sing-song voice that both irritated Shining and turned him on even more. He took a deep breath to regulate his throbbing heartbeat while his balls, feeling impossibly full, throbbed even harder. Then—not gently, but not painfully, either—he shoved his massive, flared head inside of her.

Twilight was on her back, so there wasn’t much for her to do but let her jaw hang open, her legs twitching helplessly as her brother spread her apart. “Ooh. Oh. Oh gods yes!” Her thighs, which she’d stretched out on either side, twitched and shook as Shining stretched her wider than she’d ever been stretched before. When she’d felt him stretching her muzzle, heard her jaw crack, she’d been almost afraid that he’d either snap her mouth in two or get stuck, given how big he was. But a mouth didn’t have an erogenous zone.

So instead, all Twilight felt now was pleasure: a rising tide of sensation that washed up her spine and crashed right over her chest. It mixed with tightness, pain—but a good pain, like stretching a muscle. And stretched she was. She felt a fire burning in her loins, both from arousal and tightness, as her big brother’s head alone stretched her wider than any toy she’d ever attempted before.

“Oh, gosh,” she heard him grunt. “Oh, gods. Twi, you’re so soft.”

“Stop...ngh...waiting,” Twilight panted, “and stick the rest of it in!” Another mare might have been terrified of Shining’s near two-foot tool, but not her. She wanted to be filled with it, wanted to be filled by it, wanted to make herself into a cocksleeve just waiting to become even fuller of her brother’s cum. She felt and heard her belly sloshing just above her as Shining reached forward, planted his hooves on her hips, and slowly eased the next few inches inside of her.

Six inches. Seven. Twilight’s eyes almost rolled up into her head as the feeling of fullness intensified. Oh, yes. “Keep going,” she panted. Her inner walls were quivering, quenching, leaking fluids around her brother’s shaft. She wanted more. She needed more.

And Shining was happy to provide. With a snort, he shoved another five inches inside of her. A jolt of electricity exploded up Twilight’s spine, fireworks going off on the back of her eyes, as she felt a full foot of her brother’s footlong pushing inside of her. He slid another few inches out of her, his balls rubbing against the mattress. She wanted to ask him why, wanted to make him stop, wanted to tell him that he was going the wrong way—and then he slammed his hips forward and rammed all twelve inches plus an additional four inside of her.

Sixteen inches. Oh, gods. His medial ring was inside of her. His medial ring was inside of her. How wide was it? Six inches? Seven? It didn’t matter. All that mattered was that her pussy was sucking in every inch of size her wonderful, incredible big brother had to offer, and that there was even more to come.

She groaned. A strand of saliva strung out between her lips. “Oh, gods,” she moaned. “Shining, you’re so big.”

He allowed himself a smirk. Sweat was beading on his forehead from the exertion of forcing his way inside of her alone. “Big enough?” he said, knowing her answer. She shook her head, then let out a cry of pleasure and pain as he slammed the last four inches inside of her. Fireworks. Lightning. An earthquake in her loins. She trembled, shook, cried out as she writhed around his shaft. Femcum streamed from her walls—and found itself stuck inside, with Shining’s massive tool providing an airtight seal between her marehood and the world outside. Oh, gods. Was that her womb?

She didn’t know. All she knew was that there were twenty inches of incredible, thick, stallion cock inside of her. There was only one thing to say.

“Fuck me,” she cried, and Shining did just that.

His hooves roamed hungrily over her rump, squeezing and rubbing her flanks as he drew back his hips and shoved back into her again and again. She groaned, twisted, moaned while his hips rocked back and forth. He couldn’t even pull all the way out—his stallionhood was just too huge—so he just pulled out to the length of his medial ring before plunging back inside of her. Twilight Sparkle just screamed and cried out in pleasure. She wanted this. She wanted him. She wanted all of this and more—faster, harder, deeper.

Shining’s massive balls, far too large to hang between his legs, instead just rocked back and forth in time with his thrusts. Their cum-filled depths sloshed and churned as Shining plowed his little sister, their oceans of seed swelling every time he hilted himself inside of her. Even though he’d just cum buckets, he was feeling incredibly, painfully pent-up. He needed to fill her up, needed to empty his cum-laden orbs inside of her. Shining felt his entire consciousness focused at the base of his shaft, and felt the pressure growing even more incredible with every thrust.

“More!” Twilight demanded. “More!” Her plush belly was wobbling from side to side, bouncing like jello with every thrust. Shining snorted, whinnied, tossed his mane as he squeezed her flanks even harder. Twilight could feel him pounding her womb, could feel him filling up every inch she had to give. But that wasn’t enough. “More!” she demanded, and her horn began to glow.

Shining didn’t realize what had happened at first. All he knew was that his pleasure had suddenly increase a hundredfold. He slammed his cock inside of her again and again, each time plunging even more of his size into her tight, dripping depths.

He was growing even larger. Twilight’s eyes rolled up into her head as Shining’s shaft hit—and passed—two feet in length. His balls swelled up, their spooge-filled contents sloshing and churning even more as they got big enough to actually start pushing his cock up and away from the mattress. Shining snorted, moaned, as his cock began to shudder and lurch with an insatiable need to cum inside of Twilight’s marehood.

It kept growing, passing twenty-eight inches without breaking a sweat. Twilight couldn’t breathe, couldn’t shout. She just stretched her mouth wide open in mindless ecstasy as orgasm after orgasm racked her body. Shining passed thirty inches, with a girth nearly as wide around as her waist. She caught it out of the corner of her eye—a massive, meaty bulge pushing out of her stomach, pushing past even the gallon or two of seed he’d filled her up earlier. Again and again he rammed into her, deforming her belly, plunging deep into her womb and stretching her very body around his cock like some kind of enormous condom. And Twilight just kept on screaming silently, her magic on a runaway mission as her body just kept lurching and writhing in absolute pleasure.

The scent of his own stallionhood was intoxicating. Shining groaned aloud as he struggled to keep his load down. He could feel it growing, swelling, sloshing in his enormous, cum-laden nuts. He needed release for those warm, heavy spheres. He needed to—

“Fuck me!” Twilight cried out, retrieving control over her vocal chords for a moment. He saw the massive bulge in her stomach, and for the first time realized what it was. “Fill me up. Breed me with your seed!”

Shining didn’t need to be told twice.

With a roar of impossible pleasure, he let the pressure in his loins go free. Instantly, the muscles of his hips tightened, flexed, jerked wildly as his thrusts lost all semblance of rhythm. He bottomed out in Twilight instantly, then groaned and snorted, panted and whinnied as copious amounts of ejaculate flooded straight into his little sister’s womb.

The cascade of cum crashed into Twilight’s insides, filling her up with a single spurt and going even past that by the second. Jets of spunk spattered audibly inside of Twilight’s womb as Shining’s massive, straining nuts released a torrent of cum inside of her. He fired shot after thick, gooey shot, her womb swelling up to join her belly and passing it in volume in a matter of seconds.

On and on he went, pumping out more and more spooge until Twilight’s belly had swollen up past the point of mere pregnancy. She looked about ready to bear twins—no, triplets—and still Shining’s jizz came. He slammed his shaft into her again and again as the spooge in his nuts churned and roiled. This was his release, his promise of love to his sister: this tidal wave of spooge, this erupting volcano of seed that would bloat her up until all of the world could see that she was his mare, until all of the world could see how much he loved his little sister.

He came for a good thirty seconds more, a veritable ocean of cum spilling out of his throbbing, lurching shaft and filling his sister up even more. Each rope of cum added another few cups of warm, creamy spooge to her swollen depths. Twilight’s grasp on sanity had long since left her, and she’d been reduced to moaning, shrieking in pleasure as her belly overflowed her grasp and actually fell past her sides until it touched the bed. She was full, so impossibly full. She needed this, needed it so badly. She wanted it to keep going, wanted it to never end—

Shining panted as he drained what felt like every last ounce of cum from his nuts. He let out a final cry as the last thick rope of spooge shot from his three-foot tool with the force of a rocket, then fell back onto the bed, all his energy spent.

The warm afterglow was already washing over him. Clouds began to drift across his mind. He closed his eyes as the last peak of pleasure rode him out and evaporated inside of him. Oh gods.

He was actually still inside of her—with a cock over three feet in length, just falling back onto the bed hadn’t done enough to dislodge his massive member from Twilight’s cunt. Twilight just moaned as her brother’s cock slowly went flaccid inside of her, reducing her stretch from insane to merely impossible. She wrapped both her hooves around her sloshing, cum-filled belly and wasn’t surprised in the last when she couldn’t reach even halfway around it.

“Fuck,” Shining said between pants. His tongue was hanging out of his mouth. His body shook with every breath. His hooves were trembling. “Oh fuck.”

“That,” Twilight breathed. “That was incredible.”

“Yeah.” Shining closed his eyes. Sweat was streaming down his forehead. “Oh, fuck. Thank you, Twily.”

She was more than a little bit indisposed in her current position. Her cum-bloated belly had to weigh as much as she did. Still, she was able to shift her legs, somewhat awkwardly, so that they were curled lovingly around Shining’s still throbbing tool. “Mm,” she murmured. “Thank you.”

He smiled drowsily at her over, or at least attempted to. His massive package and her enormous, sloshing belly kind of made eye contact a bit difficult. Still, it was nice to at least make the effort.

“We should do this again sometime,” he said.

“Yeah,” she said, sounding dreamy. “We definitely should.”

Suddenly, something slammed downstairs. “Kids!” Night Light’s voice sang out. “We’re home!”

Both Shining’s and Twilight’s eyes opened wide. “I thought you said we had two hours!” Shining hissed at her. He needed to try and get up, try to leave the room, but his package was so heavy, and he felt so warm, so slow…

“I...ngh...did!” Twilight grunted, struggling—and failing—to budge beneath her ponderous, cum-filled bulk. “They told me nine!”

“The restaurant was closed!” Twilight Velvet’s voice floated down the hallway. “So we decided to come home and have a nice family dinner together.”

“Fuck, fuck, fuck,” Shining was chanting. They had to hide, had to escape, had to stop this, somehow. He managed to swing his body around the side of the bed—pulling his massive member out of Twilight’s pussy with a loud-sounding schlick and letting a few pints of his seed cascade free—but tripped over his own enormous balls, landing straight on his face. The floor thumped.

“Everything okay?” They could hear hoofsteps approaching the room. Twilight Velvet sounded concerned. “Shiny, are you in there?” The unmistakeable sound of a hoof on the doorknob reached their ears.

Shining and Twilight thought the exact same word.

Shit.