In the confines of their shared bedroom, a curious sister can't help but steal glances at her brother's growing bulge. "Starting to get hard, huh?" she teases, her voice laced with newfound curiosity. As he shifts uncomfortably, she watches his cock tent his shorts, her own body responding with a warmth between her legs. Their dynamic shifts as she openly admires his growing manhood, her gaze filled with a mix of sisterly concern and forbidden desire.