The brother's pulse quickens as his sister's tongue swirls around his sensitive balls, drawing them into her warm, inviting mouth. She knows he's close, and she loves the power she holds over him. She sucks harder, feeling his cock throb against her cheek, as he tries futilely to push her away. The room is thick with the scent of their arousal, and the sound of their bodies colliding fills the air. He can't hold back much longer, and the anticipation is almost too much to bear.