Rumble couldn’t believe what he’d learned. Dinky didn’t even let him cum inside her anymore, because if he did, they’d make a baby! He didn’t want a foal, and he told Dinky he wouldn’t put a foal in her belly, but he really wanted to put a foal in her belly. He wanted to feel himself in there, just… cumming, and… and he even wanted Dinky to give him nasty looks while she swelled up like a melon.
But she wouldn’t let him, and then something occurred to him that just kept him up way past his bed time, so turned on by the thought, he just couldn’t stop masturbating. What if Dinky didn’t know he came in her. Then Rumble wouldn’t get in trouble, and Dinky wouldn’t even know to be mad at him. How could she possibly not know? Well…
Rumble honestly didn’t know how to do it with Dinky, because her mom kept the doors and windows locked. But he saw the open window at his neighbor’s house, and he actually knew Cloudchaser a little. Sometimes they’d be out front together, and he’d say hi, and the point is she had a vagina… and if Rumble could cum in that, he’d make her pregnant. Because that’s what stallions did, and that’s what Rumble wanted to do every time he stroked himself.
Dinky was sad that he wasn’t doing sex with her anymore, but it serves her right for trying to not get pregnant. Rumble didn’t know why she wouldn’t want to be, but it was her loss, he figured. Because Cloudchaser had no idea, and… he could get to her.
Sneaking in through the window, Rumble was lucky enough that it was Cloudchaser’s bedroom. Heart hammering in his chest, if he got caught he’d have to run, and she might see him. Then he would get in trouble. But he wanted inside a vagina so much, that he just didn’t care anymore. His penis got erect just looking at the sleeping mare on the bed.
Rumble wasn’t stupid, he’d had sex with Dinky enough to know how it worked, and that it needed to be wet. He brought some of his brother’s lube. He rubbed the lube into his penis, quickly getting hard and stiff, and feeling so good he had to bite his lip not to moan. He masturbated not just to himself, but at the mare on the bed. Cloudchaser didn’t know he was doing it, and somehow that made it even more enticing.
He didn’t stop there. He kept going, and bucking into his hoof, until Rumble could feel the urge to ejaculate rushing up in him. He saw Cloudchaser, lifted the edge of her blanket and saw the spread legs, the soft feminine V in between them that he was going to impregnate. She didn’t wake up then, and carefully, though still stroking himself, Rumble climbed onto her bed, under those blankets. She still didn’t stir. He poked her leg, then touched it more firmly, then started stroking himself again, and soon as Rumble felt it, he lifted Cloudchaser’s leg just enough to he could wriggle his groin up close to her. Absolutely terrified she’d wake up, he pushed his penis into her labia, and was…
He was inside her.
“C’mon…” Rumble whispered to himself, gently hugging her leg as the burning heat of the sleeping mare enveloped his dick, and all the times he’d ejaculated into Dinky came rushing back to him. He was thrusting, and grunting, and the feeling rushed up again, the urge. Rumble fucked in short, deep strokes pressed up against the sleeping mare’s groin, until it absolutely overwhelmed him, then… he pushed deep inside Cloudchaser’s vagina. The climax singing through his veins turned into a rhythmic pumping in his penis, and Rumble couldn’t see very well under here, but he could feel the mare he was impregnating. He put every drop, deep as he could. Then Rumble…
Then Rumble was done.
He slipped out of her and gently lowered her leg. She didn’t even stir. He looked at his work, and the sleeping mare’s groin looked sticky, but lay there serene, full of Rumble’s seed. Squirming off the cloud bed, he tip-hooved across the room, and fluttered up silently, flying out the window before turning back and looking at the cloud house before him. He did it… it worked. It was like a dream. Rumble had never felt so fulfilled. He just got away with murder practically.
And a few days later, he was back to do it again, just to make sure. Three times, four times, the weeks passed, and Rumble was out playing in front more often, just to have a chance to see the weather mare. Cloudchaser always smiled when she saw him on flying into her house. She had no idea and Rumble was gonna get away with it scot-free.
That’s what he thought the fifth time, there in the dead of night, inside Cloudchaser. Rumble gave a slight grunt as he climaxed, and a gratified smile crossed his face. With his young balls pressed up against her groin, his penis felt so thick and powerful buried inside Cloudchaser’s birth canal, as pulses of seed rushed up it, deep into her. Rumble looked at the smooth curve of her pelvis in the dim light, his hot squirts happening inside there, feeling like this mare was changing pregnant even as he pumped his seed into her. Without any hesitation, Rumble eagerly ejaculated as deep into Cloudchaser as he could go, right up into her receptive womb.
Rumble didn’t risk it anymore after that, mostly because Dinky started letting him use a condom, but it was enough. Cloudchaser’s smile was a little more worried when she flew in sometimes, like she was hiding something from Rumble, and Rumble knew exactly what it was. Her belly started… growing. Rumble tried not to stare at it, knowing that he did this to her. That was the foal he put inside her.
“Are you having a foal?” he asked one day, trying to sound surprised.
“Oh, y-you noticed, huh,” Cloudchaser said, blushing and lifting a hind leg. “Not exactly what I had planned. Maybe the condom broke? I don’t get it, it just kinda… started. And here I am.”
“I bet you’ll make a great mom,” he replied, cheerfully,
“Yeah I just… I can’t believe it’s finally happening to me,” Cloudchaser said faintly, looking off into the distance. She focused on Rumble then and said, “I–I know I’m an adult and all, but I still feel like a filly.”
“Well you can’t possibly feel the same as before you had a foal in there!” Rumble protested impishly.
“It’s true,” Cloudchaser admitted, “Guess it is making me feel more grown up or… something. I mean, I’m making a foal. Not consciously I mean, but every time I eat, or breathe, or even move, I’m pumping… stuff into my belly, and it gets more and more like a real pony every day. I just…” She took a long, deliberate breath. “There,” she concluded, “I just made the foal bigger, just by taking in oxygen, and getting it into my belly. And I’m gonna keep doing it over and over again, u-until I can’t stop… giving birth.”
“You can’t stop?” he asked a little weirded out by her wording.
“Yeah, they say once labor starts, it just keeps getting stronger, until all you can do is…” Cloudchaser blushed, “Can’t even imagine myself pushing a kid out of there, but with this belly, I sorta… can.
“Don’t know why I’m telling you all this,” Cloudchaser said to Rumble, leaning on her cloud fence, “I don’t wanna burden you with some mare’s clueless troubles. You’re just lucky you don’t have a… er… girl place.”
“You aren’t enjoying it?” he asked critically.
Shaking her head, Cloudchaser said, “No, I can’t not enjoy it. Even now I’m like… man it’s gonna be cool giving birth. It just gets easier to think about the further along I am. When I found out I was freaking out, and now I’m… different. So that’s just kinda weird, and you’re lucky you don’t have to deal with that.”
“I guess so,” Rumble said solemnly.
“You sure you don’t want this inside you~?” Rumble teased, teeth biting down on the rubbery condom that he’d filled with seed, buried inside little Dinky Dew’s hot vagina. The end was full of his white seed. “One little drop and you’ll be pregnant,” he said soothingly, “You’ll start growing a foal in your belly. You wanna a big round belly just hanging under you? You wanna feel the foal in there… feel it coming out?”
Dinky was blushing heavily at the slightest of his words. “N-no,” the filly said unconvincingly, “I-it doesn’t matter if I want it that’d just be stupid… filly thoughts. Birth hurts, and I… I don’t wanna do it. And my mom would kill me if…”
“You’d be a mom too,” Rumble contested, “She did the same thing, to make you, and my mom to make me. That’s what you wanna do, so why not do it? All you need is my seed in you, and your womb’ll start making a foal as hard as you can.”
“I–I couldn’t be a…” Dinky trailed off, laying back and rubbing her belly. “Oh Celestia, I can’t believe I could make a foal in there. A-all you have to do is ejaculate, and it’d… and a foal’d be inside there.”
“You’d make a foal in there,” Rumble purred, “Every time you ate, or breathed, you’d be using your womb to make the foal bigger. Your body’s already ready to make a foal; you already know how, even if you don’t know it. You just need my seed, and then you’ll start… doing it.”
Rubbing her entrance with a hoof, Dinky looked at the condom longingly, but said, “N-no, my mom would kill me. I just can’t…”
Rumble hummed, and he had an idea of what to do about that.
Dinky slept splay-legged on her back, incidentally, and without a blanket that summer, which made it easy for Rumble to just… squat over the sleeping filly and push his climaxing penis into her labia. He hardly had to thrust at all, before the hot spurts of his ejaculation were shooting up his penis, deeper inside the hips of the murmuring Dinky, And not a drop leaked out, with her groin resting there slightly tilted upward, between her… slightly twitching hind legs.
He watched the sleeping filly getting pregnant with his child for a moment, before leaving Dinky to her rest, and quietly gliding out the window, making sure to shut it on his way out. He was glad that their locks weren’t too hard to get past after all. Because in a couple days, he was going to visit somepony else in that house…
Some time later, Rumble couldn’t help but blush as Dinky came inside his new vagina again, surrounded as he was by a half dozen mares with foals on their backs, watching him accusingly. He really didn’t know if giving birth to 7 foals in a row was a fair punishment, because that meant there were gonna be 14 foals running around, but at least he could be with Dinky again. He was already pregnant with his first, but Dinky was perfectly fine with working on the second one, once she found out how good it felt to cum inside a mare as a colt… and once she found out he’d impregnated her and her mom.
“Best… punishment ever…” Dinky groaned, almost too quiet for Rumble to hear, as she clutched his rump close from where she was mounting him, and Rumble felt the soft spurts of Dinky’s seed start to flood into his birth canal.
“s’not… so bad…” Rumble gritted out as everything beyond his lungs felt like they were tearing him a new one, “Dilation is… nnngh!”
“The best part about it is I’m next,” Cloudchaser said, strutting up to the sweating, scared, contracting young stallion. “Soon as you get that foal out, I’m gonna put one right back in.”
“M-maybe I…” Rumble said, contracting fiercely, “Will—! Keep… it in…”
Cloudchaser responded by teabagging his muzzle. “Maybe I’ll let you smell it, while you keep giving birth,” she purred, “Because you can’t stop doing it.”
Rumble couldn’t take his eyes off Cloudchaser’s new fuzzy testicles, and her swollen sheath ready to erupt with horsecock, even as his uterus overwhelmed all his senses with the power of its’ contraction. It didn’t hurt is the thing! Except it did! He couldn’t comprehend what he was feeling, any more than calling it the biggest “good pain” that he’d ever felt. He was doing what his body needed to do, and even though it made him scream with the …effort of it, the more he felt himself stretch open, the more he wanted to do it. Not pain so much as total sensory overload.
Rumble stared at that swinging penis coming out, the one that’d do this to him, as he helplessly gave birth as hard as he could. The foal slipped through him, and a panicked attempt to keep it inside was swiftly overwhelmed by the urge to contract again and again. He cried out in… fear? Passion? Pain? He clenched and squeezed, until the foal was sliding out of him, and that only made him want to do it more. Then it was hanging out of him, then it was… gone.
Suddenly empty, Rumble took in two ragged breaths, then lifted his head, and Cloudchaser’s penis hanging there booped his nose.
Of course, his vagina was really sore afterwards, and the doctors made Cloudchaser wait at least a few days. But it wasn’t long before Rumble approached the public arena, ears folded, looking up at Cloudchaser. Instead of apologizing, again, he meekly turned his rear, and lifted his tail.
“Oh I’m gonna enjoy this…” Cloudchaser said eagerly, walking up to nose Rumble in the still sore gonads. “I haven’t cum since transforming, the past three days, and I’m gunna feel the first one in your sweet little pussy.”
“Not so little anymore,” Rumble grumbled, considering that what came out of it had been nursing at his teats not ten minutes ago.
Still, when Cloudchaser mounted him, and her dick slid up inside his birth canal, she stiffened atop him, saying, “Holy—Celestia, you’re warm in there!”
Holy Celestia chose not to comment on this.
A few experimental thrusts, and Cloudchaser was thrusting into him enthusiastically, moaning, “Oh stars this’s why you impregnated me. Oh stars and—I am gonna cum in you so hard.”
When she climaxed, she was a little less surprised than Dinky. Dinky had been like, “I—I think I’m cumming! Do you really wanna… I’m gunna… just keeps getting bigger and…!” she jammed deep in him, biting out, “It’s… it’s… aah!!” as the first spurt of jism leapt out of Dinky’s cock, and Rumble suppressed a moan at the feel of the filly eagerly pumping him fell of seed. “Hap…ning…” was all Dinky managed to say through gritted teeth while ejaculating hotly, with her penis buried deep in Rumble’s snatch.
The larger Cloudchaser had a different reaction, moaning, “Oh fuck it’s getting close. I’m gonna cum as a dude. Fuck I wanna… wanna do it…” and then her thrusting grew ragged, as she said, “Oh fffuck yeah. It’s… more and… more gonna… hahhh…” She jammed her penis deep into him, and growled cutely into his ear as her kicking penis started spurting thickly into his womb, “Can feel… it pumping… you’re pregnant you little… twerp…”
Rumble realized it was punishment, but as his vagina healed, and returned to its unpregnant state, he found himself presenting eagerly for this new mare’s cock, not just wanting to get it over with, but wanting to feel it in there, to climax helplessly around it, and feel Cloudchaser’s penis… changing him too.
And so Rumble celebrated his 18th birthday without too much trouble, after giving birth to his fifth foal. He really felt like he was starting to get the hang of this labor thing. It was almost down to a science at this point. His womb, cervix and such knew exactly what to do, and he was just hunched over doing it like crazy for an hour at most. With how easy the fifth came, Rumble was starting to regret that he couldn’t stay a girl after the seventh.