Isaac understood what Derek meant. There were some Masters who would use training tactics, that he was sure his Master wouldn't agree with. For some reason they thought it was okay, because the human needed to be 'broken'. Isaac knew better. Looking up at his Master, Isaac's brain turned to a puddle of mush, when he was presented with the possibility of a reward. Anything he could think of seemed both silly, and un-askable, at the same time. His eyes dropped down to the sofa.
"Oh, I couldn't, Sir.." he stammered. "Serving you is enough of a reward."
The thought came to him immediately, filling his head, and making his cock twitch. He knew it wasn't right, to keep it from Derek, but he couldn't say it.