He's spectacularly impressive at the whole not-thinking thing, Leareth muses, as he sits down in his workshop and stares tiredly at a wall covered in diagrams. Leareth isn't sure he would even be capable of that.
He's pretty thoroughly convinced, at this point, that some incredibly powerful alien force has mistreated the young man very badly. Nayoki described the memory modification to him. Said that she doesn't think it could be done by a Mindhealer even in theory.
He's...correspondingly unsure how much of the information he thinks he has is even true. Arbitrary memory modification is terrifying. It still seems probably true that whichever Power did this to the young man couldn't have known to plan specifically to confuse Leareth, but - maybe not, if the snake monster was a fabrication too, it could be that this Power which might or might not be named Melkor did figure out how to travel to other worlds, and is trying to trick Leareth, specifically, into following some course of action that will end up serving his aims...
As usual, trying to outscheme gods is the sort of thing that makes one feel as though they're going insane, and alien gods is even worse.
He'll do one more week of research on the premise that the young man's pre-capture memories are unaltered, he decides, and after that - especially if he's not making much progress - he'll take more extreme action.