2T4U/Jack/Fucking Melony/Grab her and roll over so that she is on top
You look down at her with a knowing smirk. She definitely wants this, and now you are going to prove it to her. “Ok then,” you say as you take your penis out and lay it flat against her stomach, you lay your whole body down on top of her and get yourself between her legs, then you roll over with her in your arms.
“Eeeek,” She shrieks at this unexpected action. “Jack, what are you doing?”
You roll her over on top of you and set her up, her on top cowgirl style and you below her laying on her bed. You look up at her confused face, smiling snidely at what you are sure you have just proven. “Ok then,” you say to her, “I'm gonna bet you want this even more than I do. Time for you to prove me wrong.”
“Jack...” she responds, her face contorting in indecision. “No, what's wrong with you? I don't want to have sex with my brother!” Her words are hardly convincing though, taking in the fact that her hands have dropped down to your chest and she has started grinding her pussy very hard on the shaft of your penis.