The air in the room is thick with tension and the scent of forbidden fruit. The sister, her big tits straining against her shirt, turns to her brother, her eyes filled with a hunger that mirrors his own. 'I know what you want,' she purrs, her voice a smoky whisper. She reaches out, her hand wrapping around his hardening cock, feeling its length and girth through his jeans. He groans, a primal sound, as she begins to stroke him, her touch igniting a fire within him that can only be extinguished by the sinful act they both crave.