I Had No Idea

Picture this. You're at home, going through your mail, when your step-sister gets home from her day on campus. She's in a pleated skirt, knee-high socks, and a white button-up blouse. You've known each other for a short while, but you can't really get her out of your mind - even when she's pestering you for a night with the car. As she heads up to her room to study, you catch a glimpse up her burgundy skirt - there's a flash of purple panties before she slides out of view. You make your way upstairs and peek through the doorway… There she is. She's sitting at her desk, legs wagging back and forth as she peruses her textbooks. But you can't get your eyes off the delicious mound of her pussy restrained by her panties pressed against the chair's cushion. Is she grinding back and forth on purpose…? God, ever since she moved in with you, you've heard her whimpering and moaning as she masturbates and it drives you crazy. Does she know how much you crave her? Maybe if she knew how big and ready your cock was… You slowly creep closer, pulling it out as you watch her innocently run her hands along her thighs… Is she showing you on purpose? Suddenly you lean a little bit too far and slide out of the door frame, crashing to the ground. She jumps up, locking eyes with you. Wait, hold on! This isn't what it looks like-- Fuck. Caught. What happens now?