"Nothing? And what is it when it isn't 'nothing' in a dream?" And what manner of thing exactly does it belong to? He has to mentally sit on his hands, or he'd reach for the illusion and the mind behind it, this time in curiosity rather than rage. "What can you do in the waking world?" Forgive him if he seems a bit apprehensive about the possibility of stuffed into an illusion while he's awake.