"Xas," he says, shaking his head at the proffered cigarettes. He's never smoked before, and he doesn't want to cough and sputter in front of a demon, even a very surprising one. 

It takes him a second to finish working through everything Hellboy said; the end of the world is a new idea to him, as much as the idea of a demon choosing not to be miserable and sadistic. It's like a human choosing not to be needy and grasping. He doesn't think it would be possible, where he's from, but here - all right. He takes a deep breath. 

"I'm sorry. This is strange," he says, then asks, "What was Hell like?" Maybe entirely different - he doesn't know if that would be reassuring or more troublesome.