Bulge

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.