"If I say I want your life in exchange for not siding with the singularity instead of your race, are you willing to give up your life?"
Nathan expected Cthulhu to show a bit of his rage because what he was asking was truly ridiculous. How could he even demand the life of the Old One like him?
However, Nathan knew that Cthulhu wouldn't kill him. If what he said about his rule earlier, it also meant that Cthulhu would be considered helping him if he killed him. He helped him from the torture he was about to go through. It could be considered a mercy killing.
If Cthulhu showed his rage, he would find out that the matter between the alien race and the singularity hadn't deteriorated to the point where it was more important than even his life.
Nathan was trying to play a war of words to see Cthulhu's stance. Yet, to his surprise, Cthulhu didn't show any reaction.
He replied as though he had prepared the answer all this time. "If my life can end this war, I'd gladly offer it to you.