Derek and Allison meet at a party, Derek offers her a ride home, they talk and they start to like each other. Lydia suggests to Allison that she should "give him a little taste", and Derek hears (thanks to super werewolf hearing). Derek goes over to Allison's house but he's scared that he's not gonna control his werewolf powers, so he tries to leave, but Allison convinces him to stay, so he does. They have sex, and they keep on seeing each other and all, and then one night Allison discovers that he's a werewolf. She's scared at first, but she can't seem to pull away from him even after that.
Derek tries to make her leave, several times, so he won't hurt her, but she refuses and continues with whatever 'thing' the two of them have.
That's an idea I had for a fanfic but I don't know how to write good stories, so I decided to tell you if you're interested :)