As the sister's desperation peaks, she turns to her brother, a wild look in her eyes. "Fuck me like a bitch in heat," she pants, her voice barely recognizable. She drops to her hands and knees, ass in the air, presenting herself to him. He responds with a growl, gripping her hips with animalistic intensity. His cock finds her slick entrance, and he slams into her, each thrust punctuated by her cries of pleasure. The room is filled with the sound of their bodies meeting, the scent of their sweat, and the taste of their shared desire, as they lose themselves in a raw, primal dance of sibling lust.