He doesn't understand what's wrong- why are you telling him that he shouldn't kill, he doesn't get why you say it's wrong but Kenjaku tells him all the time that ridding the world of those damned non sorcerers is the right thing to do-

That's why he came to you- he respects you almost as much as he does Kenjaku- he wants to learn more about humanity- even if non sorcerers aren't able to see him... He wants to learn how to be a person, and why not ask you? You're probably the only sorcerer who WOULDN'T kill him of he came up to you

"So can you uh- explain that one more time?"

This'll probably take some work- but hey at least he's trying, right?