In the dimly lit family room, the siblings huddle together, their breath visible in the chill. She's wearing his oversized hoodie, the scent of him driving her wild. He notices her hardened nipples, the way she bites her lip. Gently, he pulls her close, their bodies pressing together. She can feel his arousal, and it sparks her own. Their first kiss is tentative, then hungry, their tongues dancing as their hands explore each other's bodies, their taboo love story just beginning.