MATING, that's what!

Your mind has already been made up. Sierra's breasts start to grow faster. She rubs them as they grow, apparently feeling some kind of pleasurable sensation. The material of her dress magically grows along with them, the thin, slinky material gliding across her swelling mounds, always looking to just barely fit her. The rest of her body undergoes some more minor changes; her arms get a little more muscle, and her hips get a little wider, her thighs a little thicker. Her face stays largely unchanged, well, aside from the fact that she's biting her lip and closing her eyes and her expression is just *so* damn erotic in a way you've never seen it before.

When her transformation slows to the point it's not noticeable -- it never truly stops, when girls are affected by your cock -- her eyes open again and she looks down at her tits eagerly.

"Wow, they're so big!" she says, pulling down the strap of her dress. It slides off her massive udders, collecting around her trim waist. They're magnificent, way bigger than Ashley's, each easily surpassing her head in size, drooping delectably like teardrops almost down to her belly button. Her areolae are dark and surprisingly small, especially compared to her puffy, deep brown nipples. It all looks ridiculously huge on her petite frame. She giggles and shimmies her body a little bit, making them sway and jiggle enticingly, then she cups one and gropes it. Her hand almost disappears in the soft flesh. She bites her lip again and looks up at you gleefully.

"Fuck, I'm so hot now. And I know *just* how to thank you~"

She steps forward. She's so short, your cock is so long, and her tits are so big that, from where you're sitting, the head actually reaches to their underside. She pushes her massive mammaries together and starts lowering herself. Your cock helpfully puts out a little spurt of slick precum, easing its passage into her cleavage.

Sierra watches your face carefully for your reaction as she starts to pump the demon in and out of her breasts. It feels really good. You lean back and blissfully let her do her thing. Your cock is happy too, temporarily distracted by its new mate's body. Her soft mounds caress it lovingly, and soon she reaches down to fondle the heavy nuts dangling between your legs, feeling their weight.

"So potent!" She breathes. She sounds so nerdy. It's cute. You realize that you've actually had a huge crush on her for a long time now. You actually *want* to fuck her, and she actually *wants* you to be happy. This is a very different feeling than you've had the rest of the day so far!

She sees you relaxing and smiles warmly. "Hmm, you like? Should I use something else?"

The implication hangs heavy in the air. You and your cock both want it. "Yeah," is all you say.

The cute coed pulls down the rest of her dress, standing before you in just a black thong. Her pussy is drenched. She turns around, showing off a slightly improved derriere, plump and heart-shaped. Her boobs are so big you can still see most of them when she's turned around. "How do I look from behind?"

"You look *amazing* Sierra," you reply. She smiles sweetly at you and wags her butt a bit.

"Really? You want me?" She says it like she's trying to talk dirty, but you can sense real self-doubt behind the question.

You reply quickly. "Of course. I've always wanted you! You're beautiful, Sierra. You didn't need my demonic cock for that."

She turns back around, arms crossed beneath her massive jugs. She looks surprised. "John, I..." her face blushes and she rubs her legs together. "Nnnngh, I can't think without that stupid cock inside me!"

She pushes you on to the bed, your dick standing proudly at attention, and leaps up nimbly so she's straddling you, grinding her pussy against the throbbing monster. She pulls aside her thong, a useless garment now, and starts to press her hungry pussy lips against the flared head.

At first, it seems like the demon wasn't going to widen her pussy so it could enter. It looks almost preposterous, that you would be able to fit it inside of her; her virgin slit isn't even half as wide as the head. But, as she presses against it, gyrating her hips and moaning, some magic happens and it starts to slip in. You easily slide into her tight, molten passage. It's so tight you feel like your dick with snap off if it weren't magically altered. At first she carefully tries to control the speed, squatting above you, but soon a silly look comes across her face and her muscles relax. Her entire body slips down the shaft and she cums, hard. You hurriedly clamp your hand over her mouth before she lets out a scream. Her vagina pulses around you in waves, slowly petering away as the intense orgasm wears off. When she regains her senses she looks at you with slightly glazed eyes, and she puts her hands on your chest, starting to fuck against you slowly, a little timidly. Her gigantic tits bounce heavily against her slender ribcage, jiggling delectably. She looks you straight in the eye.

"Holy fuck, this cock... John..."

Your hands instinctively grab her hips and she starts to bounce a little faster, trying to find a rhythm. You bounce back in to her, watching her enormous breasts jiggle. You can see the obscene outline of your cock through her slim stomach, the tip pushing the back of her womb all the way up between her tremendous tits. The has a dreamy smile, watching your eyes closely, clearly enjoying the way you're looking at her. Yes, your cock thinks, she's your good cocksleeve breeder fuckmeat now. Take her! Make fuckmeat happy, make you happy!

Sierra is now bouncing quickly up and down on the demon, fucking it with unpracticed gusto. You eagerly bounce back, letting yourself just enjoy her body. Loud slaps fill the room as her juicy rump slams down on your overfilled balls, each time letting out a spurt of your mixed pre-ejaculate. Not long now. Your movements get frantic, jerky, her eyes look like a rabid animal's and you're sure yours do to, the wet splap-splap-splap-splap gets faster and less rhythmic as you two approach a soul-rending climax together.

Finally it happens. You thrust upwards as far as you can go, burying the demon cock deep into her spasming pussy, and the first thick jets of sperm come out. Sierra clamps her hand over her mouth and screams into it, her eyes watering and rolling in their sockets. Her belly starts to balloon forward as gallons of cum are **** into it, making her look pregnant with just one mighty blast. More follow, and soon her tight little body simply can't take any more, and excess cum squirts out of her stretched hole onto your thighs. Her fantastic melons quiver with her body as shot after shot send you both rocketing to an incredible peak. Your vision goes white for a moment.

When you come down you don't really know where you are. Your cock is still buried deep in Sierra's womb, which has now stretched to the point that she looks like she's about to give birth. Every few seconds another quart or so is pushed into her and immediately the same amount if pushed out. You can feel a huge puddle of hot goo between your legs.

Sierra pants. "Th-thank you," she says, her voice soft and still far-away. She's barely keeping herself up. She leans forward so her face is right above yours, eyes looking directly into you, studying you. You can feel her hot breath on your cheeks. Then she kisses you.

Suddenly you have butterflies in your stomach. The kiss is long, passionate, youthful. It's the first in a long time for both of you, and so much better than you remember. You wrap your arms around her and pull her close, your cock forgotten even as cum sprays out of her distended hole.

Finally you disengage, but Sierra continues laying on top of you, her giant breasts and inflated womb weighing you down.

"Wow," is all she says, after a long silence.

"...Yeah."

"So this is... you now?" She asks, looking back at where the demon is still embedded deep inside of her. She gets up on all fours and starts to shuffle forwards, pulling herself off of it.

"Guess so. I've had a really crazy day." She slides herself forwards until your head is wedged between her huge, sweaty breasts.

She chuckles. "I bet." The head finally pops out and cum geysers from her gaping cunt, and she slides herself back down to rest on your side. Your arm wraps around her, easily finding its place on her butt. It feels natural. "How many girls have you bred so far?"

"Um, I guess technically only two, but I also had sex with Professor Pifflewhiz."

Her jaw drops. She's never had a class with the professor, but she's heard you talk about how severe she is. "No!"

You nod. "Yup, she said she needed to extract the cum for testing. To make a, uhm, way to abort this thing's babies."

"Hmm," Sierra pats her mostly-deflated womb, "Yeah, I don't think I want to carry a demon's babies. Or any really. Too much going on. But *gawd*, it felt sooo good being filled up like that, knowing I was getting pregnant."

It makes you a little sad to hear that she doesn't actually want to have kids with you, but mostly relieved. You're obviously in no state to raise any kind of child, demonic or human.

"Do I need to, like, do something? To make sure I don't pump out a demon baby?" She asks, suddenly concerned.

"Maybe. You should probably go see her within the next few hours. But I was really hoping to hide out here until the prof is ready to fix it tomorrow." Speaking of, it's pretty hungry again. And you have a nice breedable piece of ass right there...

Sierra bites her lip and rubs it. "So you mean get rid of it? I'd better take it while I can get it, then."

Your cock throbs. Your balls are filling again. You might as well take the opportunity. You push her onto her back and get on top, preparing to mount her. She grins up at you, putting her hands above her head and spreading her legs in anticipation. Her giant udders spread out on the bed, the thick nipples pointing upwards proudly. Milk starts to bead on them. You slide in easily, and before you know it you're all the way inside her, pressing your cum-soaked balls against her butt. It's warm and cozy in there, just tight enough. She smiles at you, her mouth hanging open, her eyes glassy. Your expression probably looks just as stupid as hers.

You start to thrust into her slowly, and she begins panting, closing her eyes and luxuriating as your cock slides in and out of her. Her huge boobs bounce, her nipples making big circles in the air as the milk jugs gyrate. She's in heaven. You're in heaven.

You continue rutting for hours. By the time she's completely worn out, you've pumped her full at least four times, and you've also hosed down her body and every surface of the room with your thick, gooey cum. You've decided to keep it around; you actually like seeing her completely painted white, and she thinks it's super hot too. You lay in bed with her, cuddling her cum-soaked form and lazily groping one of her giant, leaky tits. They've gotten even bigger, now officially as big as Pifflewhiz's got earlier, but looking even more absurd on her short, slender frame. They are actually the size of watermelons, if not a little bigger, and the milk they leak is delicious. She's already got a pretty big baby bump too; it's not just cum stuffing her womb any more.

After a short nap, your new breeder rouses herself. "Okay, I need to head to the demonology building, right? I'll pick up some food too. You can stay here overnight, of course."

"Thanks, Sierra." Your cock is already looking forward to more sex. Maybe she has some friends she'll invite over? You try to ignore the thought. "I really appreciate it."

You wish the cum away and she gets dressed, struggling to get her newly proportioned body into her clothes. Luckily, the demon's magic slowly makes them fit her better, and she manages to stuff her tits into a tank top. Even modified, it can barely hold the massive melons, and her belly is completely exposed. Her little round bottom fills out her jeans deliciously. She looks over her shoulder and smiles at you before leaving. "I'll be back in a few."

You lean back on her bed when she closes the door. That was very satisfying. You feel, for the first time that day, like everything's going to turn out all right. Your cock agrees; but it still wants more. Surely, you could go out for a quick fuck while she's gone?