You can't help but get turned on by your step-sister, her revealing outfits, it's like she doesn't realise the effect she's having on you. Every chance you get you either end up dreaming or day-dreaming of her. You chat to her in the kitchen while she is making lunch and end up day-dreaming of fucking her over the counter, you help her with her studies and end up day-dreaming of tit fucking her, you day-dream while she is doing her presentation in class and imagine her riding you, ending with you dreaming of fucking your step-sister in your bed and giving her a big creampie, if only it was real ;)