My petite stepsis' unusual sleeping habits

My stepsis has some unusual sleeping habits. She's always sleeping on the floor, in the weirdest positions. I've caught her a couple of times, and every time it's a bit more than just a simple accident. She's so petite and skinny, and her body is just perfect. I can't help but think about fucking her. And I know she's thinking about it too. We're always teasing each other, making fun of each other, but deep down we both know we want it. I know it's wrong, but I can't help it. I'm so fucking horny for her. I want to fuck her so bad. I want to take her from behind, while she's sleeping on the floor. I want to fuck her hard and deep, and make her scream. I know it's fucked up, but I can't help it. I'm a fucking pervert, and I love it.