Be nice and let him cum

"Well done, master," you say. "It's time for you to cum now. Don't hold back. I want every drop of your thick cream dripping from my pussy when we're done." You words make him quiver with anticipation, but nothing can prepare him for what's about to happen. He cries out, his back arching helplessly as you contract your muscles faster and harder, sucking his cock deeper into your pussy with every swift squeeze. His body bucks and you feel his cock pulse inside you, coating your tight tunnel in his warm jism.

A heady rush of sexual energy floods through you, starting in your pussy and racing out to your fingers and toes. You feel stronger, more powerful and resilient. Even your tits look a little bigger.

He collapses, gasping for breath, his whole body trembling with the aftershocks of his orgasm. Just for the fun of it, you give his overly-sensitive cock a few more slow, firm strokes, making him squirm and whimper beneath you. Too soon, though, he's gotten soft and he slips out of your tight box, leaving you empty and aching. You climb off of him and sit back, sinking your fingers into your wet snatch and rubbing your throbbing clit as you regard the dazed and gasping human before you.

Such fragile things, so easily worn out. It'll be an hour before he's 'up' to fucking again. Well, maybe a half hour. He's young. But still, it means waiting, and you hate waiting. You feel the power surging through you, and you want more. With this power, you can change your body to make you more effective at pleasing your partner. Bigger tits, longer tongue, a more dexterous tail...your predecessors have tried them all, and you smile at their memories, the successes and the failures. Then a memory really catches your interest, about chemically altering your body to produce pheromones that increase the human libido, making them horny and virtually insatiable, capable of fucking for hours and cumming repeatedly. Sounds like exactly what you need.

But to do that, you'll need more energy.