Under the covers, the siblings' bodies entwine, their breaths ragged with desire. The sister, her curiosity piqued, traces her brother's length with her fingers, feeling him pulse with need. She looks up at him, her eyes filled with lust, before lowering her head. Her tongue flicks out, tasting the tip, before she takes him in completely, her mouth hot and wet. He groans, his hands fisting the sheets, as she works him with her tongue, her lips, her throat, until he's writhing beneath her, his body tensing with his impending release.