The sister, lost in thought, sways her hips, her ass cheeks jiggling with each movement. Her brother, hidden in the shadows, watches, his cock hardening at the sight. He can't resist the temptation any longer. Stepping closer, he reaches out, his hands grasping her ass, squeezing the soft flesh. She freezes, then moans softly, her body pressing back against him, urging him on. He obliges, his hands exploring her curves, his cock throbbing with desire.