In the dim light of their shared bedroom, the siblings' breaths grow heavy with anticipation. The younger one's hands tentatively explore her elder sister's curves, pausing at the warmth between her thighs. She guides his fingers to her tight, puckered asshole, and he tentatively pushes in. She grinds against him, hungry for more, until he replaces his fingers with his thick cock. They move in sync, her ass swallowing him whole, until they both shatter in a taboo climax, their mingled fluids dripping down her thighs.