YESEYES its even better if s4p is a virgin. he wants to experience sex so bad and older sister sy1 notices the way he always stares at her tits whenever they're talking and sometimes he asks her questions related to sex and what she did for her first time. Maybe asks her who she lost her virginity to, asks how to find someone to do it with, then soon asks to see her tits. They're home alone when she flashes him for the first time and he almost instantly gets a boner over it. Then she asks if he wants to touch them, if he wants to feel a pair of tits for the first time and play around with them. Of course he eagerly agrees, barely feeling any guilt over the fact that this is his big sister. they've always been closer than most siblings, so this kinda stuff isn't too weird or unfamiliar for them. After he's had his fun playing around with her tits, she leads him to her room and asks him if he wants to see a pussy in person for once rather than just in the porn they watch. Again, he eagerly agrees, and watches with a slack jaw when she starts playing with it, slowly fingering herself, brushing her fingers over her clit too before asking if he wants to fuck her. He's so fucking hard so of course he says yes, practically ripping off his clothes before clambering closer to her and pushing himself inside once she's stretched herself enough. He's not wearing a condom, and she tells him she's not on birth control so this might be a little risky, but both of them are /way/ too horny to care about that right now. After one push and pull s4p is a whining, drooling mess and he can barely move, his thighs shaking and his dick about to practically fall off. So, she flips them over and rides him until she's satisfied. He cums very early, it being his first time and all, but she doesn't stop until he's sobbing and shaking with overstimulation.