In the hushed silence of their shared bedroom, the siblings' breaths syncopate as they steal glances at each other's awakening bodies. The moon's glow through the window casts a silver sheen on her hardening nipples and his growing erection, tenting his boxers. She traces her finger along her collarbone, down to her heaving chest, pausing at the hem of her nightshirt. His eyes follow, hungry, as she lifts the fabric, revealing her bare, quivering stomach. He licks his lips, and she smiles, her eyes never leaving his as she slowly, tantalizingly, exposes more of her flesh, the promise of what's to come hanging heavy in the air.