Author's Note

This is intended as an idea dump of sorts for my own story concepts. Please do not solicit your own ideas.

Prompt: Now in the distant future, Rarity and Spike are effectively giant demigods of life. They now are going to use a spell that allows Rarity to get pregnant even while already pregnant. They've chosen to do this at Rainbow Falls.

Based off image PASTEMEhttps://derpibooru.org/images/2386110PASTEME

Contains: Pony, Macro, Hyper Pregnancy, Superfetation

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The ponies of Rainbow Falls were about to get a show.

There were Rarity and Spike, immense beyond measure, their bodies taking up so much of the landscape they could be seen for miles. Their own size baffled them—they’d grown and grown and grown until they were the biggest creatures that ever lived. Yet even now they were still growing, doubling, tripling, quadrupling in size with each passing year.

“Spike…” Rarity shifted her grand weight. He was beautiful. That’s what went through Rarity’s mind every time she looked at him. Even now, with her belly larger than the rest of her, her rainbow-tinted mane damp with sweat, her hips wide and flanks thick, she knew he lusted for her. He couldn’t STOP lusting for her, for she may as well have been a drug he couldn’t get enough of.

And speaking of Spike, he was just as much of a marvel. A miles-tall hunk of a dragon that set her heart a flutter with merely a look. Flawless reflective scales harder than diamond glinted in the midmorning sun. Dense, heavy muscles rippled along his lithe frame. Hypnotic, green-slitted eyes glowed with life and light: fierce yet kind, primal yet calm. His wings were what she loved most—phenomenal, tremendous things that could enshroud a small mountain range.

They were effectively gods—benevolent and gentle, but gods all the same. The ancient draconic marriage ritual they’d undergone years ago had become the vessel of their ascension. Had it been so long ago that either of them could fit inside of a house? Inside of a street? A town? Had it been so brief since they looked up at mountains instead of down upon them? Rarity remembered when the growth had really started to speed up, becoming more and more astonished as each day she woke up larger, her sleeping space feeling more confined. It’d happened in conjunction with her pregnancies, each a greater brood than the last, her body seemingly growing larger and stronger. To make her into the perfect maternal figure.

She remembered back when they’d first visited Rainbow Falls with Twilight. It was a beautiful town. Even as she was now she could still appreciate its beauty—she could still hear the waterfalls faintly below. She remembered trotting amidst the stalls of the Traders Exchange and hearing the dull murmur of haggling. She remembered visiting the Falls again on her and Spike’s honeymoon, where they’d conceived their first seven miracles. That was back when she was still able to fit inside of towns and cities, able to walk amongst the buildings. It was when her womb started to press against the houses as she trotted down the streets of Ponyville she realized her days of visiting settlements were limited. Not without magic, at least.

It was a shame to have to withhold her beauty. Her greatest joy was to readily give anything and everything she could to the world. Having to withhold her true splendor meant others couldn’t witness it, and as time passed and she grew greater in every way, she had to conceal herself more and more. But it was a small price to pay for what her and Spike’s ever-increasing power allowed them to provide.

Currently, Rarity was halfway through her latest pregnancy. The most bountiful by far, but Spike and Rarity still wanted more. Not only that, they realized they could do more, and they didn’t have to wait to do it. For not only had Rarity’s increased power and size come with an increase in many other things, but also new abilities.

This was the trial run. Rarity closed her eyes as her familiar magic came to her in a rush, cool and comforting and fluid as water. Magic that altered the body, enhanced the body was not something typically done for many reasons, but Rarity understood the workings of life now. She could see the inner workings down to the very cell, even WITHIN the cells. She knew how to manipulate the very building blocks of matter to her whim.

She guided her stream of magic into her belly. The countless lives within her stirred at her touch; twitching in dreams. The flutters were less than the movements of fleas to her, but if she concentrated she could feel them, and every one made her heart soar. She continued to guide her spell deeper inside herself, past the growing lives within her into a place even more intimate—the very store of her reproductive cells.

They looked like twin caverns to her mind’s eye. Indeed, to the average size pony, they were caverns. Each was larger than a hoofball field, and each was filled to the brim with innumerable, healthy, glittering clusters of light. The sheer capacity for future life was a marvel. Orders of magnitude beyond any other creature. Mares were supposed to lose their reproductive cells over time. Rarity’s body had been making more. And more. And more. Only the barest fraction of the total was mature, and it’d been this amount that’d been regularly released as part of her cycle.

But with Rarity understanding what she did, discovering what she could do, with what she and Spike had already become, and now could become…

Rarity’s horn glowed with more magic. The countless lights within her twin caverns shone a soft blue. Newfound warmth bloomed within her as she continued to fuel the spell. A tidal wave of hormones flooded her, her face blushing and heat radiating from her groin.

Waterfalls of estrus-laced arousal fell from her marehood and to soak the fur of her plush rear. Spike caught the scent immediately, a lusty rumble escaping his chest that echoed across the valley and beyond. His mile-long dragonhood rose out of his sheath, growing and twitching, an entire reservoir’s worth of pre escaping his impossible tip to slick up his even more impossible size.

“Now?” Spike asked.

Almost panting, Rarity looked back and into his face. Saw the eagerness that mirrored hers. She nodded.

Spike growled and clutched Rarity harder. He leaned his weight into her, clutching her soft fur and feeling the rasp beneath his digits. So long, and thick. Rarity’s beauty was without peer: the colors of her rainbow mane glittered and shone at all times like flowing water. Signs of blooming health shone throughout her body, from her thick, soft coat to her pristine hooves. His scales were so smooth along her body. She could feel him gripping her, claws stroking through her coat, his wings wrapped around her. Oh, she loved it when he did that. So warm, so smooth… she never got enough of the feel of his strong, taut muscles that could wrap around her and make her feel safe. Even at her biggest he’d been able to wrap them around her with ease, and now they could literally blot out the sun. She inhaled deep and caught a familiar scent… his scent. She turned her head back to kiss him, and he eagerly obliged, letting loose a jet of flame in her mouth that sent a prismatic ripple across Rarity’s body.

Spike plunged his girthy cock into Rarity. A wonderful, warm shaft, so thick and BIG. His dick alone was larger than all of Ponyville. Rarity cried out at his touch, not in pain but in need for more. Spike leaned a bit more of his tremendous weight, his great core muscles flexing and pushing, giving that extra bit of oomph, the inertia alone making the surrounding air waver. He pushed more, feeling her soft walls envelop him. So soft and silky, so inviting, so willing, so pliable and supple. How many times had he molded them to shape now? Beyond count, certainly, but yet he still wanted her. Beyond words, beyond sensation, beyond even a dragon’s greed.

Spike shivered and pushed harder, biting his lip as her pussy swallowed more of his shaft. Rarity mewled and egged Spike on faster, but he was still gentle, giving her ample time to adjust. IN and out, in and out. With every thrust Spike pushed deep, her herculean size never failing to satisfy. He was gentle when wanted, rough when the mood called for it, but his own style was unpredictable. Rarity could, no pun intended, rarely predict his technique, and she preferred it that way. Kept things fresh. Sometimes she corrected him, even occasionally taking the lead, but something deep inside her liked to be taken, just as much as Spike liked to take.

“Ah...” She shuddered in time with Spike’s thrusts. Spike thrust his hips deeper and got more of his great size in, but there was so much more left to go. She could feel Spike pause, gathering himself up for a moment before pushing his mammoth cock back up into her, causing her to moan low and long. Spike licked her salty neck and pushed deeper, feeling Rarity’s tunnel eager to accept him. The wonderful BURN of her muscles being stretched to new limits was pure ecstasy.

Not to say Rarity just laid there and let Spike do all the work. She moved with him as much as her bulk would allow, flexing her inner muscles around his great size and making him work for every yard. It was an astounding spectacle from the ground—had any bore witness in the valley, their sky would have been a colossal pair of pony and dragon genitals. Spike’s nuts were so big they took up most of his lap. He needed both claws just to cup one of them, and at the rate his package was outpacing the rest of him, in a few years’ time they’d be too big for even that.They felt so heavy and full nearly all the time. The only times they didn’t were when he’d just cum several times (almost always in Rarity) and even then the feeling was temporary. He loved it, though. He loved the fullness, what it meant, his potential continuing to climb without end. A single look at his beloved was all he needed to be ready to go, and his stamina was to the point he didn’t know if he could be tired out.

Were they making love for the sake of pleasure they would’ve gone on longer, but this lovemaking carried intent. Spike was beyond ready by the time his knot bruknoshed against Rarity’s dock. He could feel her nethers spreading to claim it, stretching even further. What felt like barely inches to her were in reality closer to a quarter mile. Spike’s knot was so sensitive he could feel every slight give, every bit of change. The tingles were unlike anything else, but it was even better when she was fully enveloping him, when she’d TAKEN him.

It was impressive, really—no matter how big each of them grew, Rarity still managed to take Spike’s fully flared knot. There was a point where he always had to push proper to get inside, and he was nearing that point now, but she could always, always take him. They could both feel Rarity’s nethers spreading more, little by little, Spike’s knot being squeeeeeeeezed by her fierce, all-encompassing need. He slid a little deeper in, a sharp intake of breath escaping his lips. Rarity gasped, hungrily so, and so he followed up the push with a second. NOW it was enough weight. They both moaned long as they felt his knot pop inside with a force that caused multiple sonic booms.

The stage was set. The lights within Rarity were waiting. Spike’s twitching cock was where it belonged. Spike cocooned Rarity in his great wings as he felt that tingle, that deep rush come from inside. His lap-filling nuts visibly clenched as he felt his peak approach. His orgasm was an eruptionthat sent lakes worth of hot, hyper-virile cum up his several thousand-foot long spire. Eyes glowing, her coat shining, Rarity cried out as Spike flooded her with several hundred million gallons in a single shot. Her deepest barrier soaked up the seed like a sponge that never seemed to be completely filled, allowing lakes worth of cum to enter her nourishing womb.

“YES!” Rarity clamped down on Spike with all her might. She could feel her magic working, feel the blooming heat of Spike’s seed flowing up into her. The wonderful, warm, full contentment of being with foal was already intensifying. She ran her hoof against the warm surface of her coat and shuddered. She was going to make sure he claimed each and every one of the lights she’d just brought into being.

Rarity cried out in ecstasy as Spike’s second surge billowed into her. It was already starting to happen. The sparks of life were spreading throughout, taking root inside her walls. Entire clusters were being claimed by his seed while even more formed. Spike’s essence had merged with hers to multiply. More essence was claimed, more sparks of life spreading through her, and best of all, Rarity could FEEL it happening. Feel her belly growing warmer, heavier. Feel Spike’s potent seed take!

Rarity’s womb rumbled. The sound echoed across the valley like an approaching storm. She was getting more pregnant by the second, and her blush only intensified with every throb, her body shifting to accommodate the lives within. The tiny glints grew and grew until they’d caught up with their older siblings, and as a result Rarity’s belly grew as well, billowing out in every direction and sinking further into the earth. To think there had been a time Rarity had been concerned about her weight. Now she was gaining thousands upon thousands of tons of baby weight by the second, revelling in her maternal girth expanding beneath her hooves. Moments of internal tension were relieved by surges further outward, and Rarity egged the sensation on as Spike’s third pulse of wet heat knocked her up that much more.

Rivers, forests, plains and hills of the valley were engulfed by an avalanche of warm, taut flesh. Preserved by magic, of course—it wouldn’t do to make a mess—merely momentarily pinned and breathing the lovely scent of Rarity’s shampoo. Those watching at Rainbow Falls could only marvel as the two gods mated, Rarity’s colossal head looming over the village, her night-colored mane swaying with Spike’s incredible thrusts. Even knotted he was still trying to push deeper, his incredible hips rocking both of them. Rarity’s gently waving locks were like the northern lights.

Spike hissed a delicious hiss. With every surge he clung to Rarity, back arched and wings flared, smiling a triumphant, fanged smile. There was a fire in his eyes, a need that raged in him, and a magic that neither fully understood. He released a particularly potent surge into his beloved, and Rarity bit her lip and shuddered, the tight spring in her core snapping free like lightning. She suddenly felt a tight, tingling warmth in her breasts—each one of her mounds already contained enough nourishment to feed legions, yet they now swelled still larger, pushing out past her legs and pressing hard against where she and Spike and Rarity were joined.

Rarity could feel the change in the air as her belly rose higher, higher, higher. Her belly’s mass alone slowly eclipsed both her and Spike combined. So many. So full! Eventually she and Spike would grow to catch up with her new additions, but for now her womb dwarfed them, dwarfed everything, so large it could be seen from space.

It went on like that for a while. Spike’s balls were mighty, but eventually even he petered out. Yet inside Rarity his efforts continued to bear fruit, both of them watching with eager eyes as multitudes of offspring formed before their very eyes.

The available acreage in the valley dwindled more and more. The edge was marked by train tracks winding along a mountain ledge, miles from Spike and Rarity, but Rarity’s womb was an approaching landslide. It was just as her now city-sized navel kissed the tracks that her womb gently wobbled to a stop, the new lives and swirling fluid settling within.

Rarity smiled. It seemed their little trial with this spell had been a success. Every last one of the lights she’d released had been claimed. A new son or daughter. Rarity could feel their presences come into being, and already she loved each and every one of them. And she didn’t even need to look back at Spike to know that warm smile on his face, that excited glint in his eye. Neither of them didn’t fully understood why any of this had happened, but they were going to make the absolute best of it. The only question now between them was how they used this new spell in the future.

To that note, despite how many eggs Rarity had released, she’d only used a fraction of Spike’s seed.

Rarity bit her lip. All that hot, virile dragon cum, ready and waiting inside her...

…

Perhaps a few more babies wouldn’t hurt.

Or a few million…

A few trillion—

GURRRGLE

Spike chuckled. He’d seen this coming a mile away, of course. He nuzzled Rarity’s neck and gently stroked Rarity’s expanse of womb as he watched it grow in subtle throbs. All was taken into account. Their foals would be loved and cared for. The world would be a better place for their existence.

After all, what kind of benevolent gods would they be if they couldn’t provide for their family?