In the dim light of the attic, the siblings' breaths hitch as they tentatively touch, their hearts pounding with a mix of fear and excitement. The sister's hands tremble as she guides her brother's cock to her virgin entrance, their eyes locked in a mix of apprehension and desire. He pushes in slowly, his body tensing as he feels her barrier give way, her gasp filling the silent room. They move tentatively at first, their young bodies learning each other's rhythms, before finding a steady pace that leaves them breathless and panting. Their first time is marked by the sound of their bodies slapping together, the smell of their sweat and arousal filling the air, and the taste of each other's lips as they explore their newfound desires.