“Alright, easy now. One step at a time. Be careful, you can do this. “

Princess Celestia grunted and panted as she made her way through the halls of the Canterlot. Her afternoon strolls had become increasing difficult as her pregnancy progressed. What had started as a small bulge in her belly had eventually ballooned to a taut basketball, and was now bigger than a beach ball. She had to spread her back legs far and wide in order to accommodate her swollen womb, which was packed with no less than four large foals. When she first agreed to have children with Luna, solely for the good of Equestria of course, she had no idea how virile her sister was. She sighed as she rubbed the massive swollen dome with one hoof. “Well, at-least we’ll have a strong dynasty now.”

Despite being swollen up larger than any mare before her, there were a lot of perks that came with the new situation. The entire country was now in a buzz about the news of four new royalty about to be born within the next few months. That meant Celestia was able to indulge herself in festivities, fine feasts, and other luxuries even more than she’d usually be able to. On top of it, Luna had taken it upon herself to do more and more of the workload, giving Celestia even more time to relax.

Too much relaxation came with some side-effects, however, as Celestia was reminded as she went to enter her personal quarters and found her hips brushing against both sides of the doorway. All that extra food she’d been eating hadn’t just gone to feeding the growing foals, but also found it’s way into all of her curves. Her hips, which could have already been described as “motherly” before she became pregnant were now the embodiment of fertility. Four foals would seem like an impossible task for most mares, but for Celestia it would be very achievable What grabbed the most attention, though, was her flank. It was already the bounciest, plumpest, rear in all of Equestria. Now it was that and then some. Her backside usually meant the end of any chair she’d try to sit on, and she already had to order a larger throne as her plot cheeks plumped bigger and wider in response to all the new calories she was taking in.

She heaved herself on to the bed with a sigh, and promptly glared as the piece of furniture groaned in response to her weight, “Curse you, I don’t weigh THAT much….”

There was a giggle from the doorway, “Putting curses on the inanimate objects now, are we?” The source of the giggling was soon revealed to be Luna, who was the cause of both Celestia’s dilemmas and her pleasures as of recent.

“Oh..um..just letting out some frustration is all”

“Mhmmm” Luna smiled approvingly as she made her way over to Celestia’s side and took in her sister’s maternal form. She began to rub her sister’s massively swollen belly with both hooves while smiling up at her. “So, how’s our favorite sister been?”

“Other than feeling like an over inflated balloon, I’m alright. Although it’s hard to stay focused on anything when you’ve got four foals kicking around inside of you.”

“Is that so?” Luna looked over Celestia’s middle with curiosity as she began to rub a bit more intently, feeling up every inch of her belly’s slopes. She could feel her heart flutter slightly as she felt a definite kick against the edge of Celestia’s womb, and then another a few seconds later. Meanwhile Celestia herself began to moan lightly thanks to Luna’s administrations.

“Enjoying yourself?” Asked Luna with a smirk.

“You have no idea. This belly rub feels like heaven after carrying around this giant dome all day.”

They spent a few moments like that, with Celestia gratefully enjoying the tender belly rub she was receiving from her sister. Then Luna began to get a bit more creative. She stretched out her hooves to the limit and managed to grab hold of Celestia’s belly from both sides. She then gently rocked it back and forth while holding her ear up to it and enjoying the sounds of sloshing amniotic fluid and swimming foals kicking against the walls of their mother’s womb. Luna was still in awe of this whole situation. To witness her sister’s fertility in action, and to be the “father” of her children on top of it.

“Now who’s enjoying themselves?” Asked Celestia in a cheeky tone.

Luna blushed, not realizing how distracted she became, “Heh...sorry sister. It’s just not hard to get entranced by your new figure..”

Celestia smirked, “Do tell more.”

Luna smiled in response, having played this routine before. “How could we not be distracted by such a form? After all, you have the biggest, most rounded womb in all of Equestria. A true display of superior fertility. Not to mention the most motherly hips any of us have ever seen, topped off with such a...prestigious flank.” Luna smiled lecherously at the end of that sentence as she grabbed large hoof-fulls of Celestia’s plump flank; squeezing and groping shamelessly. She couldn’t help but smirk as Celestia squirmed with arousal. Speaking of arousal, she was beginning to feel her own flare up along with a throbbing between her legs. She could pounce Celestia and rut her right now, but it would be so much more satisfying to let the lust build first.

“And let us not forget the newest feature,” Luna smirked as she made her way lower to gaze upon Celestia’s burgeoning breasts. They had swelled rapidly since the onset of her pregnancy, and now resembled two plump melons. There was no doubt that the two mounds were filled to the brim with milk for their upcoming children. It was so tempting to lean down and suckle from those supple teats, but she restrained herself. That milk would soon be required by some very needy foals.

However, there was something much more naughty Luna COULD do to those delightful breasts. She reared up slightly and slowly slid her quickly hardening and lengthening member in between Celestia’s tits, enjoying their soft and squishy embrace.

“Oh my, sister...what are you…?” Celestia struggled to see over her massive belly before she realized what was going on, “Oh you naughty little Parasprite…” She responded to this realization by bringing her legs closer together and tightening the hold her breasts had around Luna’s shaft. Luna promptly groaned in response as she began to slide in between the milk jugs faster and more fluidly.

Celestia could only pant with growing anticipation as she felt that big, meaty shaft throb in between her breasts. She longed to feel it deep inside her once again. Despite already being pregnant, she just couldn’t get enough of having Luna’s seed pumped deep inside of her. “Luna, you tease me too much. I know you’re having fun, but isn’t it time for the main course?”

“Patience, my dear sibling,” Luna replied as she gave the side of Celestia’s right flank a heavy smack, watching with delight as it jiggled in waves. “I need time to take in this glorious sight and get prepared”. With that she re-positioned her member near Celestia’s wet slit, prodding and rubbing against it to get her rod lubricated. Beneath her member she could feel her balls churn with a heavy load of seed. Of course, there was seldom time when they weren’t. Luna had been forced to boost her production heavily to keep up with Celestia’s hormone boosted sex drive.

Celestia grabbed hold of the bed sheets and spread her legs wide, getting herself prepared for Luna’s size and usual roughness. Not that she was afraid though, she couldn’t be any more excited. After all, there was nothing like a good rut from her sister to distract her from the growing pains of such an extreme pregnancy. There was also a bit of fun added by the suspense. Since she was unable to see anything except her big, white dome of a belly, there was no way to know just when Luna was going to penetrate her. At-least, not until she felt a building pressure at her entrance, followed by the intense feeling of her marehood’s lips being parted and her inner walls being forcibly spread by the girth of Luna’s cock.

Luna let out a long, loud groan as she pushed her shaft all the way in to the hilt. She then smirked down at Celestia as she readied herself to begin thrusting, “Better hold on tight, sister. I don’t know if the bed will hold out this time~” Luna than shifted her hips back before eagerly plowing forward, smirking as the bed whined from the combined weight of herself and Celestia pressing down. She then began to repeat the process over and over, being rewarded with the rich lewd sounds of their hips slamming together. What was even more rewarding was the way that every thrust rocked Celestia’s body, sending every voluminous part of her figure bouncing or jiggling. Her massive,gravid womb bounced gently forward and back, with her heavy teats slapping against the underside of it. Meanwhile her plump thighs and heavy flanked jiggled in connected waves, cushioning Luna’s heavy thrusts.

Luna leaned down to gaze happily into Celestia’s eyes, panting with pleasure as she began to thrust even harder and faster. “Mmmh, you’re so amazing, sister. Truly the most fertile mare in the land. With the largest, most motherly figure on top of that. Your hips and posterior are almost wider than the bed, and that belly of yours could almost serve as a small chair~”

Celestia blushed even deeper than before, moaning passionately as her sister rocked her world in more ways than one. “Are you sure about that? Maybe you can get me even bigger the next time, can’t leave any records un-toppled after all”

“Now there’s a thought,” replied Luna in a husky voice. Her cock began to throb even harder as she imagined what Celestia would look like if she had an even more fertile form, and was laden with even more foals. Just the thought of filling Celestia full of more and more offspring drove the more animalistic parts of her wild. She began putting all of her power into pounding away at Celestia’s slick snatch, ruthlessly plowing her with abandon. She imagined her sister’s belly swelling bigger, and bigger, and bigger. She’d be so large and fertile that any other mare would drop with envy.

The bed creaked and moaned as Luna pounded away at Celestia like a feral animal. The sounds were only contested by Celestia’s wild moans and screams of pure pleasure. She couldn’t do anything more than hold on and enjoy the ride as Luna’s rod slid in and out at such a heavy pace; along with her large,heavy balls slapping hard against her soft rear.

“Hold on tight, sister. Mmmhh..not much longer now~”

It was their most intense rutting yet. Luna’s shaft throbbed hard and eagerly while Celestia’s slick inner walls clenched ever tighter, as if trying to milk Luna of all her seed. It was seed the Luna was eager to provide, as every erratic thrust made her testicles ache for release. Meanwhile Celestia began to scream louder and louder, until she finally screamed Luna’s name in pleasure while her marehood clenched up tight as can be.

“Ohhhhh, Luna!”

“It’s coming, Tia!” Luna tightly held Celestia in place as she finally began to release her pent up load, spurting thick cup fulls of splooge deep into her sister’s tunnel. Then another, and another. Celestia could only squirm with ecstasy as she was pumped full of the same foal batter that left her so unbelievably pregnant in the first place. However, she couldn’t help but feel a warm contentedness as Luna emptied nearly immeasurable amount of seed into her, but was surprised as Luna’s thrusts began to slow down.

“Finished already, Luna?”

Luna smirked, “Not nearly, but I had an idea” she then slipped her cock out of Celestia’s snatch before taking aim and shooting out heavy streams of sticky fluid over Celestia’s body. She worked to coat every inch of Celestia’s ample curves with her seed before collapsing next to her sister and panting heavily, “That was….quite excellent….sister.”

“Easy for you to say,” replied Celestia,” “You’re not the one who has to deal with that in your fur. But I’ll forgive you, if you’ll help me with the bathing~”

“I’d be delighted.”

Author's Note

Finally got around to posting chapter 2. I feel like tackling a 4th story soon, but I'm not sure what. I'll probably make a blog post with a poll to see what people would be most interested in.