To make a deal

"Wonderful!" The demon said, still slowly moving up and down the dildo fastened to the throne. "Then allow me to introduce myself properly. I am called Lilith, and my domain is sex and lust in all forms. Your display today was a very rare thing for mortals, at least to do it with the enthusiasm you showed, and I wish to reward you for it. Therefore, regardless of what you say to my deal, I will grant you this boon: For the next day, you will be able to change your body in any way you wish. Want bigger boobs? Smaller ones? Another hair colour? Or do you want to grow a dick and see what it's like to be a man for a while? It can all be done. Just remember that any changes still in place when the day is up will remain permanent..." Her grin grew wider. "Unless you agree to work with me, in which case I will extend that to continue as long as our deal goes on."

I stood there, struck by what she'd just said. While I was in no way an ugly woman, I certainly had my share of teenage insecurities, not least of which were my still rather small boobs. Father had always said they'd grow in time, but I knew there was no certainty of that, and patience was not one of my strongest suites. Also, this was something I'd already earned, so there would be no drawbacks to use this reward, right?

"I can see you are thinking over the possibilities. While you're doing so, is it okay if I present the deal I'd want with you? You can of course ask any questions about it that you wish."

I nodded.

"Great! See, I have long wanted a mortal agent. Currently, your catholic church has way too much power over sexuality, and I need something, no, someone, to adjust that. So what I'd want you to do is simply to continue like you have, and make sure you spread the joys of sex as wide as you can. And I'm not just talking about you fucking around, but to make sure others are doing it without you as well. Do what you can, both by personal example and by political power, as well as whatever else you can come up with, to make sure that your species fuck as much as possible. Do you understand what I want out of you?"

I nodded again. This didn't sound half-bad at all. After the last day's activities, I'd known that sex was something I'd want as often as humanly possible anyways. And the rest... well, my father was basically already doing that, wasn't he? Basically, what I'd need to do was just to keep up his policies, and maybe expand on them a little, once I'd inherited him. This was all stuff I'd probably do anyways, demonic deal or not. However, I knew better than to say that. Instead, I asked "What would be in it for me, then?".

"Ah, you have learned well, child. I can see your arousal at the mere thought, and I think you would do this regardless of any incentives I would give you. But, I am a generous being. First, of course, as long as you keep up your side of the deal, my reward will stand, you will be able to enhance your own body. Secondly, you will not age. This means you will be immortal, as long as you uphold the bargain, but you will not be invincible. Old age will not touch you, and you will have greater resilience to most diseases, but you can still die from injuries or accidents. Or, if you annoy the wrong people too much, from "accidents". Thirdly, you will be completely immune to any diseases spread through sex, and you will yourself be able to determine, on a day-to-day basis, whether or not you are fertile that day. This is my offer", she said. "Do you have any more questions, or are you ready to accept it?"