As the snowstorm rages outside, the siblings huddle together under a single blanket, their bodies pressed close for warmth. The brother's breath hitches as his sister's hand brushes against his crotch, feeling the hardness tenting his pants. She looks up at him, her eyes reflecting the flickering firelight, and he can't resist the silent invitation. He kisses her, hard and demanding, his hands roaming over her body, feeling her curves through her thin nightgown. She shivers, but it's not from the cold. He lifts her nightgown, revealing her naked body, and lowers his head to taste her, his tongue exploring her folds as she arches into him, her moans echoing in the small room. He enters her slowly, filling her up, their bodies moving in rhythm as the storm outside rages on.