The sister's big, shapely ass fills the frame as she bends over, dusting the furniture. Her brother, unable to tear his gaze away from her plump cheeks, adjusts his pants to accommodate his growing bulge. He's always admired her big ass, but now, seeing it in motion, he's overcome with desire. He steps closer, his hot breath on her neck, and runs a hand over her ass, feeling the soft, warm flesh. She gasps, her heart pounding, as she realizes his massive cock is pressing against her.