Derek groaned, a soft vocalization of approval meant for Isaac's ears, as he continued thrusting, using Isaac's mouth with a roughness he'd rarely let himself exhibit with the boy, for fear of triggering memories of his previous Master.
He let himself get lost in the devotion he saw in Isaac's eyes, that made his stomach twist with desire, and within moments, his fingers clenched tight, his hips going still, as he emptied into the boy's willing mouth.