The siblings huddle together in the dark, their hearts pounding with fear and something else, something they can't quite name. They've been taught that their feelings are wrong, sinful even, but they can't deny the pull they feel towards each other. They start with a kiss, a soft, sweet press of lips that quickly becomes something more. Their bodies respond, heat and desire coursing through them. Their hands explore, touching skin that's soft and smooth, feeling the hard planes of muscle beneath. They're lost in each other, their bodies moving in sync, their souls intertwined. It's only when they hear their parents' voices that they're pulled back to reality, their bodies still trembling with the force of their shared desire.