In the dim light of their shared room, the brother and sister begin to undress, their eyes locked onto each other. The sister, her large breasts heaving, straddles her brother, grinding her wet pussy onto his hard cock through their underwear. He grips her ass, squeezing and kneading the flesh as she moans in his ear. She pulls down her panties, revealing her shaved pussy, and guides his cock inside her. They fuck slowly at first, savoring the forbidden pleasure, but soon their pace quickens, their bodies slapping together as they chase their release. The sister comes first, her pussy convulsing around her brother's cock, triggering his own orgasm. They collapse together, their bodies slick with sweat and cum, their secret safe for now.