Naturally

Closing the distance between the two of you, you plunge your cock deep within her walls, her intense arousal providing plenty of lubrication. She screams out in pleasure, instantly pushed to orgasm, and even as her body shakes you start to quickly and efficiently pound her quivering sex, both hands holding onto her legs so as to keep her steady as you do. There's nothing tender, passionate, or loving about the intercourse- it's simply you taking advantage of her carnal need, a need that you helped but didn't quite create.

Alicia's screams of pleasure, moans of desire, and short gasps for breath quickly fill the small room. On the other hand, you are stoically silent, almost concerned- this is what the demon wanted, after all. While it dampens your enjoyment, you still can't help but feel the pleasure of the woman's walls around your cock, desperately tight against its girth. Within a minute, she's had at least three orgasms, but you can also feel yourself approaching the threshold, though it feels slightly unnatural, as if you're being spurred on by some other feeling.

Not thinking much of it, you slightly slow in your strokes, and pull your dick from between her legs. She lets out a quick moan of protest, but doesn't continue, clearly exhausted. The arousal continues to build in your body, even without the feeling of penetration, and you quickly use a few strokes of your hand to remove the last mental barrier between you and orgasm. Cum sprays out of your cock as if it were a firehose, quickly leaving long lines on Alicia's skin. Standing where you are on the bed, you angle downwards, and start to methodically spray her body with semen, encouraged by her cheers of pleasure. What you're unaware of, however, is that anywhere the white liquid touches her skin, the skin is slowly turning a bright pink underneath.

It takes almost as long as the intercourse itself, but eventually Alicia's body is completely coated with your cum, and all you can see is a white, quivering mass. Then it starts to shift, the pile moving slowly, and when she reaches up a hand to brush off her face, you realize that her skin has turned a bright shade of pink, her eyes a piercing orange.

Underneath the covering, her pert breasts start to expand, increasing in size until they're only slightly smaller than your own, nipples growing out almost a full inch. Her sex also grows in size, the walls of her labia extending outwards from her body, and becoming much more flexible. Two small points poke through the cum covering her face, and you quickly realize that they're horns, at the top of the forehead just below the hairline.

"Delicious, mistress." Her voice has a new tone to it, playful and seductive, as she smiles up at you from the bed. "Why don't we go clean off, and show the others my changes? I'm rather eager to try out my new body..."