Not the biggest enemy, but... the most personal.

[He shouldn't be entrusting this much to a relative stranger, but he doesn't think Luke is the type to betray a confidence or use it against him.]

Our encounter in my own world left him with...

He knows everything about me. Every last detail, every secret, every part of myself I ever tried to get away from. I've made a life out of keeping myself hidden, keeping secrets. Not something I'm used to dealing with.