When Charles takes a fleeting look into Will's mind, the possible significance of that last sentence is amplified. "Yes. We're good friends." And that's all (except— )

Which also leads to, "Pardon the non-sequitor, but what sort of world do you come from?" Because Will's mind is like something out a science-fiction novel, and that's neat. "I'll understand if you don't want to talk about it, and it's only friendly curiosity on my part. Only I can't help but keep wondering why we were all brought here." Yes, that's his reasoning and he's sticking to it.