Responses
He was VERY casual about throwing up - I am not sure it was related to the kiss. There's something up with Guwon physically so.. I wouldn't be surprise if puking had nothing to do with the Teacher and this is a redhearing.
The whole talking to the Mirror tho... I don't know what to think about it. I thought... Multiple personality? Or similar to your idea mostly.
The Guwon we know is innocent in many regard... I don't even think he knows or understand what the Teach wants from him quite yet either.
You know what. I'm going to try not to jump to conclusions here so I'm going to say the throwing up could have been from anything. Hell, maybe Guwon does this on a regular. He seemed pretty casual about it.
More importantly. How do I take that last line?!
1) Is he talking to himself in the 2nd-person??
2) Is he talking like that because he has no memories??
3) Has he been possessed and the original Guwon doesn't exist?? (Well 2 & 3 are pretty similar).
Ah well. It's a wait and see.