You are alone jacking off on the bed and you see your older step-sister come in. She is surprised and shocked, yet strangely turned on. She encourages you to stroke your cock. She is impressed by the size even though you are younger than her. She starts to strip and fondle herself. She continues, getting completely naked and playing with her clit.
She knows all the boys in school want to fuck her and she is going to let you, her step-brother do it. You get on top and fuck her. She moans in pleasure and tells you how good it is. She thinks mom and dad will be home soon, so you need to cum soon. You shoot your load deep inside her and she loves how it feels.