My dealings with him started when he posted a thread about how his (quite conservative) Christian family members didn't accept his Paganism, and got mad at him when he insulted their religion and forced him to go to church. I responded the way I think most people here would, with a bit of a whack upside the head and a "their house, keep your head down until you're out of there, and consider it a good time to visit the library and learn as much as you can-- and for fuck's sake stop insulting their religion if you ever expect them to respect yours". To my surprise, he seemed to listen to my criticism, and over the last few months has come to view me as, basically, that helpful old lady who knows shit and who will give him advice. Most of my advice has been finding various resources to point him at and say "go read that". He takes to being told to do homework about as well as I'd expect from a fluffy teenager, but some of what I say clearly does manage to lodge in his brain.
I don't ever laugh at him or tell him he's full of shit, even when he is, because he looks up to me, trusts me at least somewhat, and I want to encourage him to learn to think critically and analyze his UPG without saying "no! what you're doing is wrong!" and scaring him off. But damn, does he come up with some doozies. He mixes pantheons like a frat boy mixes drinks, his patron god is a Japanese thunder demon who (coincidentally! I'm sure!) was in a video game, and now he's decided that he's Otherkin. To wit, that he's a reincarnated kobold in a human body. (Which are also coincidentally in video games! Detecting a pattern here?)
I'm officially out of my depth. I'm not much for the woo to begin with, I don't have the first idea how to answer this confession other than "you no take candle!" or "you just want to be special, hopefully you'll grow out of it", and that'd be a violation of his trust. He seems to take pointed questions reasonably well if he thinks they're well-meaning, but I just don't know what the hell to ask him, or what to point him at to stop the slide into "I like this, so therefore it's my soul". He's got a repressive home environment, has been bullied, is fantasy-prone, and I think it's important that he has someone who will neither rubber-stamp every stray fantasy he has nor make a joke of him. What would you do with this if you were in my position?