Celestia inhaled as she felt the weight pressing down against her rump. The pressure was familiar, but the size and shape unmistakeable. She shivered, her shoulders tensing as the twin weights between her flanks wedged themselves even further between her prime rump's cleavage.

"Good evening, Sister," Luna purred. "Enjoying the evening festivities?"

Celestia grunted under her breath. "Most certainly," she exhaled. She'd only half-expected Luna to do this - her sister's libido had been legendary even in the olden days, and their sisterly rituals...infamous. All the same, she thought with a muffled groan, she hadn't expected her little sister to mount her in the middle of her own welcome-home party!

Celestia swallowed, but her body instinctively pushed her legs further apart to make more room for Luna's burgeoning length - or lengths, plural. She couldn't see them - daren't see them, even, for fear of what either of them might do if she turned around - but Celestia could certainly feel the weighty, lazy throb of the twin equine shafts grinding against her rear. She'd done her part to play up the myth of the Royal Rump over the past century or two, but it was quite another thing to have her little sister rubbing her dripping, engorged lengths against it.

Unflappable in even the worst situations, a thin, almost invisible tinge of red emerges on Celestia's cheeks as Luna's breath warmed her ears, her sister's weight - reduced, but still heavier than a normal pony's - pressed down against her rump. She heard Luna chuckle softly.

"And you," Celestia continued, her tone measured, "appear to be enjoying yourself as well."

"Oh, yes!" Luna pushed her weight forward. That had the side effect of pushing her twin, throbbing shafts further up between Celestia's asscheeks, letting her fat flares slap wetly against Celestia's shoulder blades as they swelled further. Celestia sucked in a breath, struggling to contain her own sudden arousal as Luna's cocks drooled precum all over her back, the flood of it running over the sides of her barrel. Luna cooed softly as she nuzzled her big sister's iridescent mane, and Celestia could feel the beat of her heart through the fat, black member pressing into the small of her back. "A wonderful night. It's so good to be back and whole again - and especially with my big sister."

This time, Celestia couldn't prevent the muffled grunt that slipped from her lips as Luna rocked her hips backward. The massive members rustled wetly across her fur as they were pulled back. Another bead of sweat on her forehead, Celestia noted a stallion from the main floor of the "Welcome Home, Princess Luna!" celebration staring at her. She did her best to smile in his direction...though the serenity of her divine smile was interrupted by a sharp squeak! as Luna prodded the ends of her twin shafts against her big sister's taint.

A low, winding hiss escaped Celestia's lips as Luna eased her way inside. A marehood that had never taken better than a well-endowed Guard made eager way for one massive member as the puckered star of the Sun sucked in the other with the zeal of a long-lost friend.

"A whole day," Luna murmured. She nuzzled Celestia's shoulder, feeling the flex and ripple of powerful alicorn muscles beneath her lips. "A whole day back in Equestria, and my dear sister hasn't properly welcomed me back."

Celestia shuddered with pleasure as a few inches of Luna's mammoth lengths slipped inside of her. Endowed behind the dreams of mere mortals, an alicorn's sex was of all and none, leaving them both equipped with hyper-hungry wombs and twin shafts that couldn't help but overstuff any hole they found. Already, Celestia could feel her own stallionhood throbbing, swelling, as her two members pushed their way out from the confines of their sheaths. They plopped out beneath her, each one already the width of her foreleg and as long as an earth pony's erection...and yet still mostly soft.

"I - couldn't," Celestia mumbled. Heat rose to her face, and she heard Luna grunt behind her. Reflexively, she shifted her hindquarters to allow her sister better access to her winking pussy. "Aides - paperwork. So much to do. I thought, perhaps in private - "

Luna's hips gave a little jerk - that little one that Celestia had known since they were mere foals, Luna's fat, pre-slick flare scraping against the entrance to her womb - and Celestia squeaked reflexively. Already, she could feel her belly growing weighty with precum as Luna's other shaft buried its way deep inside of her, her warm, slick walls welcoming it inside with every inch - and soon, she realized with a moaning shudder, every foot.

"But we're together now," Luna cut in. She pushed forward, lodging another full foot of her length inside Celestia's belly. Celestia groaned, and automatically moved her hoof up to rub at her middle. Already, she could feel the gentle curve of her coat around Luna's engorged flare...but she knew how big her sister could get, and this wasn't anywhere near her largest.

Luna's cock jerked inside of her, and Luna purred in contentment. "It's been too long, Tia," she cooed.

Celestia's shoulders relaxed. That old name flicked a switch inside of her, and for the first time that evening - since Nightmare Moon had returned, in fact - she felt herself release a breath that she'd been holding for what felt like days.

"Oh...yes." Curling her lip, Tia let her eyes flutter shut and shifted her rear end's weight. Luna allowed it - welcomed it, in fact, as a half-foot more of her lengths was buried inside of her sister's rump. The two alicorns groaned together, lust, pleasure, and love mixing in a simple exhalation of sensuality.

"It's been far too long," Tia grunted. Her cheeks reddened, and she felt her hips swaying, wriggling as if to wedge even more of her sister's girth inside of her. Her stomach welcomed in the hefty flare of Luna's top member, receiving a cascade of precum - a liquid meal from behind - even as her womb itself was penetrated. Celestia squeaked out a moan as Luna pumped her hips promisingly, hinting at more.

"Mm." Luna lowered herself until her body was draped over Celestia's larger one, her own hooves just barely touching the ground. Her ballsack, huge and soft, draped low below her belly, each testicle easily one foot across. Tia sucked in a breath as she felt the twin orbs press against her own - and then whinnied, a little bit louder, as she felt the familiar warmth of Luna's magic surround them. Her crotch warmed, her twin members rubbing against the great bulges in her belly as her royal nuts churned with gallons more cum, their volumes increasing by the second.

For a second, though, Tia breathed out - and Celestia breathed back in. "B-but, my little ponies," she gasped, even as Luna thrust her hips forward. She last syllable was squeaked out, reaching a crescendo of pitch as reverberations of pleasure shivered through her body. "They don't know - times have changed - we shouldn't - "

Luna's words were simple, but her voice was low, deep, rich - and hungry. "We are alicorns," she growled playfully. She hugged both hooves around Tia's swelling barrel even as their endowments swelled larger in size. Already, Celestia's twin shafts were poking between her forelegs, their incredible girths actually forcing her to spread her hooves further apart as the width of her members filled up every available inch of space. Luna just hugged harder and murmured, "We are sisters. And you, dear sister," - she pumped her hips forward, bottoming out inside of Tia - "have yet to properly welcome Us home."

Tia had no response but a groan, a simple rumble of pleasure as Luna's cock bulged out her torso. She could feel Luna's weight growing heavier, could feel her sister's legs lengthening around her barrel as more and more of her sister's power was returned to her. Princess Luna had returned from the Moon diminished - but now, buried balls-deep in her big sister's dripping cunny, she was regaining that strength with every breath they shared.

Huge amounts of pre, flooding out by the cupfuls, splattered messily across the floor. Celestia bit her lip as she watched her massive cocks lurch with throb after throb of arousal, each pulsating wave of pure, bestial need driving her knees weaker. The white, milky flood gushed out like waves crashing over a beach, the puddle of arousal growing larger with each tremble of her knees.

More of Luna's precum, in turn, gushed out to fill Celestia's belly. "Nice and warm, sister," Luna purred, stroking Tia's great, bloated gut, feeling it slosh with the gallons of precum inside. Already, she could feel Luna's great, furred nuts drooping down against her back hooves even as Tia's own testicles swelled up nearly as large. Luna chuckled softly, and her members bucked appreciatively inside of her. "It's like you missed me, dear Tia."

Celestia grunted. "A-always," she groaned out. Then she gasped. Luna had pulled out her entire lengths - and then rammed back in. The sound of flesh smacking against plump, well-endowed flesh filled the area around them as Luna's panting grunts reached her ears.

"Lower," Luna growled. Celestia felt a quiver of arousal in her overstuffed nethers, and obediently lowered herself down. She pressed her chin between the cleavage formed by her two massive cocks, and lapped hungrily at the streams of precum between them. Meanwhile, Luna grunted pleasurably as her sister's hefty, well-fed ass was thrust up into the air, perfect for a proper rutting.

Celestia squeaked as she felt Luna's cocks delve even further inside of her. Then, blushing, she noticed just how many of their subjects were staring at them. Blushes, wide eyes, and trembling gazes came from every angle. The ballroom, which had buzzed with activity, all but fell silent as the sound of smacking flesh filled the air.

"Luna - " Celestia choked out.

"Almost - there!" Luna grunted. She heaved in a breath, and then rammed her hips forward. Celestia let out a most un-princesslike squeal and flushed immediately after, hyper-aware of the gobsmacked ponies staring over - or, rather, down at her. Her lower lip trembled with uncertainty, but a fresh wave of arousal set her massive rump wriggling in the air above her head, drinking in each foot of Luna's torso-sized cocks as they rammed inside of her, again and again.

Oh, goddess - she had needed this. Made naked before her subjects, brought to depraved obscenity, and sexualized like a common whore - it made her cocks and cunt burn with lust and pleasure. She felt nothing but love pounding in her heart - even as the bulge in her belly pushed up far enough to press against her chest.

"Nearly, hrm?" Tia grunted, coolly. A flare of solar will, white-hot and lustful, welled up within her. She felt her cocks twitch as she lifted her head, tablespoons of hot pre dripping from her chin. "Then please, accept my final welcome - !"

Luna howled with need, release, and lust as Celestia slammed her hips backward. Their gigantic nuts, so heavy with seed now that they sat upon the pre-streaked ballroom floor, smacked together, setting their orgasms off together. Celestia whinnied, her head throwing back as she felt her massive organs bulge with climax - and then moaned as she felt Luna's do the same.

Luna snarled, her hooves digging deep into Tia's curvaceous rump as she bottomed out. The first volley of cum alone was gallons of seed, twin geysers of spunk erupting in Celestia's deepest, most intimate insides as the elder sister twisted and squirmed about the younger's penetrating lengths. Gallon after gallon of alicorn spooge, hot and gooey and thick like cream, washed out to fill Celestia's belly and womb.

Tia felt her belly bloat even larger - already the size of a normal pony from pre alone, it only grew bigger still as throb after throb of Luna's massive cocks sent every inch of her body swelling up with her little sister's load. Tears came to her eyes as she felt Luna's lurching cock spew its thick, virile load directly into her womb, her eggs fertilizing in a single tsunami of white as her cunt swelled and sloshed around them.

The pressure in her belly grew and grew, mounting until she could hold it back no longer. Tears springing to her eyes, Celestia felt her muzzle force its way open as the pressure simply became too much. Jets of Luna's spunk, so thick and gooey and pure with virility, shot from her lips. Tia tasted her sister's orgasm on her tongue, moaning loudly and pleasurably as her esophagus contracted and swallowed around each fresh volley of seed. Ropes of Luna's thick load shot past her lips even as Celestia's own members spilled out a full tub's worth of spunk onto the floor, shot after shot of dense seed washing over the tiled marble like the incoming tide.

Finally, pumped full and impregnated properly, Celestia slumped forward, completely spent. Her massive belly was near twice her size by now, and supported her so well that her hooves could barely even touch the ground, even with the bulk of her gut smooshed out beneath her. She groaned, gurgled, feeling Luna's load slosh and churn inside of her. With a gentle push, Luna shifted Tia to her side, her now-stubby hooves wrapping uselessly around her tremendous gut.

With a happy sigh, Luna removed her twin lengths and slumped against Tia's great, bloated gut. Luna nuzzled warmly against Tia's popped-out navel, and giggled when she heard her own load gurgling inside.

"Getting comfortable?" Celestia murmured. She caught the eye of one of the onlookers and winked. The stallion blushed, for all that he was now sporting a rather impressive erection himself.

"Quite," Luna murmured. She rubbed her shoulders against Tia's great belly, as if to mark it as hers. Lazily, she began to stroke her erections, the twin shafts still greatly engorged with lust.

"All that," Celestia observed, grinning, "and you're still hard?"

"Unfortunately," Luna said cheerily. She paused, then shot a grin over at the nearest group watching them. "Do you think they might like to help welcome me home as well?"