As sunlight streams in, a young man stirs in his bed, his morning wood tenting the sheets. Unaware of his sister's presence, he begins to stroke his thick, veiny cock. She enters, frozen at the sight of his engorged member in his hand, pre-cum beading at the tip. He notices her, embarrassed but turned on, continuing to jerk off. She watches, her breath hitching, her own hand wandering to her pussy, rubbing it through her panties.