Derek could read Isaac fairly well by this point, and could tell that the boy had been honest in his refusal, but that there was something he was hiding too. Something he wanted, but thought he couldn't ask for.
He put his hand on the werewolf's face and tilted it up towards his own. "It would make me happy to give you something," he said, gently encouraging the boy's honesty. "A good slave should be rewarded, and you are so very good to me, Isaac."