Accept his proposal... with a condition

Deep inside, Samson knew that Gray wouldn't give up. He also knew that he couldn't keep up his defenses long. Eventually, Gray would win either because Samson surrendered to his terms or because his brain folded in on itself. So, he decided to make a bargain while he still had some chips in his own pile.

"I'll take you at your word, but I want a condition."

"Ooh! The boy is growing some balls!" Gray giggled at his own double entendre.

Hurriedly Samson added, "It's non-negotiable."

"Naturally. Pray tell me your condition that I may evaluate it on its merits," the serious words matched poorly with the mocking grin on Gray's face.

"I get to be in charge. The whole time. I will listen to you, but when I tell you what I want to do you have to be bound by it."

Samson could tell that Gray did not like the condition. He could tell because Gray told him so.

"Fuck you boy! That's absurd," the demon half shouted, "I'm the one in charge, that's our deal!"