Their eyes meet, a silent understanding passing between them. He's always been curious, but never acted on it. Now, with his sister's encouraging gaze, he feels emboldened. He takes his cock out, stroking it slowly. She watches, licking her lips. "Let me," she whispers, taking over. Her touch is gentle yet firm, her rhythm steady. He gasps, his hips bucking slightly. She smiles, leaning down to take him in her mouth. He groans, his hands tangling in her hair. He's never felt like this, never imagined he would with his sister. But here they are, exploring uncharted territory together.