This is hetero and I have intentions of making it very mature.
Your character will be female. I would prefer if she were neko or something similar to that. Here is where things might get touchy: your character is a whore. If you don't want her to be, I suppose she could pretend that she is gonna sleep with guys, stay at their houses, and then escape before they can go anything with her, but she has to be persistent. (Like, she'd follow a guy home if she thought he was the sort that would give her food and a place to stay if she showed some cleavage).
My character is a werewolf. Not only that, but he is very unemotional and has something against felines. However, something makes him let her stay. Because he isn't trying to get into her pants, your character is interested and tries to slip into his bed. He basically just looks at her like 'what the fuck do you think you're doing' and she does things to him. OoO
After mind blowing sex, she decides he is the one and that she is going to stick around, whether he likes it or not. Whether he is a closet case or just fucking mental, he throws her out. It starts raining, he feels guilt, goes to find her, they have sex in the middle of the forest. After that, he takes her back to his house, cleans her up, and pretends he doesn't give a shit about her. Their relationship would basically be her trying to make him love her and him pretending he couldn't care less.
The emotional aspects of this would evolve slowly, but the physical ones would be fast.
Post if interested.