An Astrophysical Convergence

“My sister, you can’t be serious….”

“We are perfectly serious, Celestia. It would be in the best interest of Equestria. Given the dangers we face it’s essential to have strong warriors to ensure our security in the future.”

Princess Celestia shook her head and sighed. They had just spent most of the day helping a distant village recover from a rogue dragon attack, and then when they returned Luna had started insisting on the most ludicrous idea Celestia had heard in centuries. She understood well why her sister was making this idea, and agreed that the security of Equestrian was a problem, but the solution was very far-fetched. Out of everything they could dedicate their powers to doing, Luna’s master plan was for the two of them to...make foals.

“Absolutely not. We’re sisters, Luna, we can’t have foals together. Besides, how would we even accomplish that?”

“A few well placed spells would suffice. Regardless, our relation is irrelevant. Together we have some of the most powerful magic in existence, and my idea is the best way to combine our abilities. As a bonus, it could even be fun…” Luna’s voice trailed off as she took a moment to eye her sister’s flank, which was quite noticeable even from the front thanks to its profile.

Celestia bit her lip of the idea of her sister possessing something extra, and promptly rutting her with it. It didn’t help that there was a nagging heat in between her legs that was constantly prodding her mind to bring dirty thoughts to the forefront. How long had it been since she had a proper rutting?

“Uh-huh. Assuming I somehow decided to go along with this mad scheme, who were you planning on being the “father”?”

Luna seemed to be deep in thought as she paced a circle around Celestia, eyeing her in an almost predatory manner. “Well. I suppose we could have a drawn out competition to see who would fulfill the role. Although I’m perfectly willing to volunteer.”

“So you want me to be the mother then?”

“Well, you are already in heat afterall~”

Celestia blushed lightly due to her sister’s realization. Luna’s suggestion was becoming more tempting the more that Celestia stopped to consider it. A child created between the two princesses would be extremely powerful, and would undoubtedly grow up to be a champion of Equestria. On top of that, she had always wondered what it might be like being a mother. It certainly couldn’t hurt to try, could it? To top it all off, she’d get to experience a big,thick, throbbing…

“Distracted, Tia?”

Smack

Celestia gasped and jumped as Luna’s hoof made hard contact with her flank, sending her copious cheeks bouncing and jiggling out of control. Her mischievous sister simply snickered as Celestia turned around and gave her a slight glare.

“Getting a bit eager aren’t you, Luna?”

“My apologies, sister”Luna responded with a slight grin,”But it seemed the quickest way to recover your attention. Have you made a decision? “

Celestia nodded, “Y-Yeah. I think...uhhh….fuck it, let’s give this a shot.”

She was barely able to finish her sentence before Luna moved forward and pressed their muzzles together. After a quick gasp of surprise Celestia could feel Luna’s tongue force its way into her maw, wrestling down her own tongue in an impressive display of dominance. Celestia quickly gave up on any resistance, even giving out a few light moans as her sister passionately made out with her.

“I knew you’d make the right choice, sister” Said Luna with a wide smile, “Now let us not waste any time. Turn around and give us proper access to that supple rear of yours.”

Celestia quickly found herself blushing again. “W-What? Right here? But what if somepony walks in and sees us?”

“Then they shall get a fine show,” Luna’s reply came in an almost purr-like voice as she walked behind Celestia to get a better view.

And what a view it was…

In front of Luna was a positively glorious and massive flank. Two unbelievably plump and rounded plot cheeks sat atop Celestia’s legs, each one slightly larger than a beachball even. The fleshy globes jiggled ever so slight as their owner trembled. There was more to Celestia’s figure than just her rump though. Her rear was complemented by wide, motherly hips and some of the most full, luscious thighs Equestria had ever seen. Celestia had certainly put on a lot of weight over the years. However, it wasn’t her weight that she was known for as much as the way she carried it. Whether due to her Alicorn biology or some crafty spellwork, Celestia carried all her extra weight in the perfect places. There was no other mare in Equestria who could have an otherwise slim figure but maintain such massive hips,thighs, and flank.

It didn’t take long for Luna’s restraint to break down, and soon she found herself walking up to her sister’s ass and wrapping her hooves around both sides of it. It wasn’t until she could barely reach both of Celestia’s cutie marks that she realized how truly large this flank was. She also couldn’t help but revel in the pleasing sensation of how far her hooves sank into the soft flesh. Soon she was rubbing, squeezing, and groping Celestia’s flank in a shameless manner.

Celestia wasn’t sure if she should be embarrassed or proud at the amount of attention her flank was currently receiving. Although it didn’t take long until Luna was able to entice a few light moans from her as those hooves deftly groped her soft and sensitive rear.

“For shame, Tia. Just how much of you been eating to get such a vulgar figure?” Luna spoke in a mocking tone, but the arousal in her voice was unmistakable.

“Perhaps I’m just naturally blessed with it,” Celestia retorted, “Why do you ask, Luna? Jealous?”

“My dear sister,” Luna replied, “I don’t envy your flank, I crave it,” She emphasized her point by giving Celestia a hard spank and sending her cheeks jiggling like an ocean of jello. She practically purred as she nuzzled that soft, cushioned rear and continued groping it. “This is quite fun, but perhaps it’s time to take it to the next level. “

Celestia heard the tell-tale sound of a spell being cast and turned around to see quite the stunning sight. Luna had just used magic to equip herself, well equip herself. In between Luna’s legs was a massive member, already over a foot in length and growing larger as its owner began to stroke it with one hoof. Beneath that massive shaft hung two equally massive testicles, each one nearly the size of a basketball and undoubtedly full of powerful seed.

Celestia gulped, “A bit excessive don’t you think, sister? That’s a fair larger than anything I’ve ever taken….”

Luna smirked, “I’m certain you’ll adjust. Besides, it’ll only increase the chances of successful breeding.” With that Luna approached Celestia and slipped her length in between her two prodigious flank cheeks. She couldn’t help but grown as Celestia’s massive rear clenched and trapped her new cock inside the near cavernous crack. It was impossible for Luna to resist moaning as every new jiggle and bounce of Celestia’s ass stimulated her shaft.

Luna wasn’t the only one enjoying herself though, Celestia began to shake more and more with anticipation as Luna’s length was hot-dogged in between her gigantic globes. “Mmhh...Luna, stop teasing me and get on with it,”she whined.

Luna replied by giving Celestia’s rear a hard smack, “I’m just getting ready. Keep shaking that fat flank and we’ll be starting real soon.”

Soon Luna’s member was throbbing at full length, an impressive 19 inches of stallion. She promptly mounted Celestia and lined it up with the intent of finding and penetrating Celestia’s marehood. She began to slowly push her hips forward, thrusting her cock in between her sister’s plot cheeks. A light groan emerged from her lips as more of her length was lost inside the ocean of soft flank. To Luna’s shock, she had already pushed nearly half of her shaft in and still hadn’t reached Celestia’s marehood.

“What’s taking so long, Luna?” Celestia asked with curiosity, right before she felt something hard pressing against her wet slit. There was barely time to gasp before the pressure intensified and Luna’s thick member was forcing its way inside of her, forcing her walls to spread wide with its impressive girth. “Ooooohh...Luna…”

“Mmmh. Hold tight, dear sister. You haven’t taken all of me yet” Inch by inch Luna continued to stuff Celestia’s entrance full of her shaft. By the time she had hilted herself the tip of her cock was pressing right up against her sister’s cervix. It was a mind-blowingly tight fit, but a fit none the less.

Luna was in heaven, the sensation of having half her member trapped between Celestia’s cushioned flank and the other half deep inside her marehood was almost overwhelming. It took all of her willpower to start thrusting at a slow and steady pace instead of just rutting away like a wild animal.

Meanwhile Celestia could hardly believe the situation she was in. She would have never pictured herself standing exposed in the throne room, getting pounded by her own sister. It was like something out of her dirtiest fantasies. It was a fantasy she was happy to give herself over to though, she pushed back her hips and moaned every time Luna’s hard member rammed into her tight slit. Each impact sent her heavy flank jiggling and bouncing like an ocean of pure jello.

“Such a bountiful, motherly figure. You’ll make the perfect broodmare, Tia” Luna teased as she began to put more power and speed into her thrusts. All the while she was being treated to an amazing show as Celestia’s ass was in constant movement with waves of jiggle. The massive cutie-mark suns that stretched across her sister’s rear made perfect targets for Luna to spank. “I do hope this rump of yours keeps growing once you get pregnant. Although we may have to expand the throne…”

Celestia could hardly imagine her flank becoming even larger. She was already the most voluptuous mare in Equestria. However, she couldn’t deny the perverse appeal in brought to consider the possibility of her plot becoming even bigger and bouncier than it already was. The evidence of her fantasizing was noticeable, as she began to pant heavier and her marehood became even more lubricated than it already was.

“That’s right, sister. Take it like a good, submissive little broodmare. Mmmh, I’m going to put so many foals in you,” Luna began to increase her pace even further, causing her heavy balls to slap against Celestia’s cushioned thighs. The two massive testicles were practically churning with strong, virile seed. Her member began to throb harder and faster as Celestia’s tight inner walls clenched to massage her extensive length.

Celestia blushed heavily at being called a broodmare, but she was receiving such overwhelming pleasure from the large cock ramming her that she wasn’t able to form anything more complicated than pants and moans. Her senses were being overwhelmed by the feeling of her copious flank flesh jiggling and the deepest parts of her inner walls being plowed. All she could do was pant like a mare in heat and instinctively shove her hips back while tightly clenching the inner muscles of her marehood.

“Oooooh...keep it up, Tia...it won’t be much longer at this rate.” Luna groaned as she began wildly thrusting in and out, humping her sister with reckless abandon. Every moan that Celestia made, every bounce of her flank, and every clench of her inner walls encouraged Luna to go faster and harder. She could feel her heavy balls slowly tightening up, like pressure building behind a dam. She was just barely holding on, but it was only a matter of time before the dam would burst.

Celestia’s moans became louder and louder as Luna’s thrusting became faster and more erratic. Celestia could barely process the amount of pleasure she was receiving, she could feel every inch of that thick rod inside of her as well as every hard throb it gave off. Every pump of her sister’s hips was bringing her closer and closer to the edge. She bit her lip and braced itself, knowing that it was only a matter of time before Luna started blasting her massive load into her.

“Nnnnnng...sister….I can’t hold back…” Luna was on the edge, she could feel it. Her cock throbbed almost painfully hard while her balls continued to slosh with their heavy load as they began tightening inside their sack. She gripped Celestia’s wide flank with both hooves and began to plow into her with as much power as her muscles could muster.

And then the floodgates opened…

The pressure started at the base, only to move forward as the head of Luna’s shaft flared open to begin spraying a wide torrent of seed straight into Celestia’s fertile womb. That was only the beginning though, as every pump of Luna’s hips resulted in another wave of sperm spilling out deep inside of Celestia’s body. It became an automatic action of thrusting in and out as she worked hard to empty her massive testicles.

“Oooooh….Luna….it’s so much….” Celestia moaned and panted heavier than before as she felt the sheer volume of seed being pumped into her. Already her womb felt filled to the brim and Luna was continuing to spurt more and more batter into her. It wasn’t long before she felt her belly begin to swell slightly, growing a bit larger with every wave of sperm that was released into her.

Throb. Spurt. Throb. Spurt. Throb. Spurt

It was like a mechanical rhythm as Luna worked to breed her sister, with endless amounts of virile cum being unleashed into Celestia’s fertile womb. Her impregnation became more certain as each pump caused her midsection to grow larger and rounder as it worked to hold the incredible amount of fluid being released into it. It was already the size of a basketball, and continued to enlarge and become more taut as the onslaught continued.

Throb. Spurt. Throb. Spurt. Throb. Spurt

The room was filled with the two sisters’ moaning and lewd slapping sounds as flesh collided and sexual juices escaped to the floor. Celestia could only brace herself and enjoy the ride as her belly continued swelling to unprecedented sizes. It was now large enough to push her legs apart slightly and make her look beyond pregnant. The sheer amount of seed now inside of her was unbelievable, and Luna was still going! How much more could she possibly be holding?

Luna panted heavily as she continued to instinctively thrust in and out. Her balls were starting to feel lighter, but she knew there was still a little bit more baby batter to put into her sister. After a few more final spurts she pulled out of Celestia’s slit, allowing a copious amount of cum to spill out on to the floor, adding to the already large puddle of sexual fluids.

The two collapsed next to each other in a heap, breathing heavily as they recovered from their intensive mating. Celestia’s eyes went wide as she looked at how far out her belly had swollen. It looked very much like an over inflated beach-ball, it jiggled and sloshed as she pressed it with both her hooves. Feeling all that seed moving around inside her inflated womb made Celestia shake with a perverse sort of excitement. “My goodness, Luna. You made me so huge.”

Luna nuzzled her sister and smirked. “You think you’re big now? Just wait until the foals start growing.” She then laid down on Celestia’s squishy belly and sighed contently. “You’re the best, big sister.”

Author's Note

This was just a short little story to get me back into the flow of writing. To be honest, it didn't turn out fully as I wanted, but hopefully some people will find it entertaining.

I'm tossing around options for my next story, and I'm even considering ask for requests, but we'll see how this gets received first.