Charlie Stoker has a personality disorder — but not the Hollywood version of sociopathy.
- He has schizoid personality disorder — he's solitary, emotionally detached and weird but clearly not devoid of feeling, and has a few intense interests. His letters and accounts of his 'travels', as given in the screenplay at least, aren't the stuff a cover story is made of; he clearly has an intense fantasy life maintained, one where his family didn't essentially abandon him. He is capable of pretending to be sociable and charming, probably through study, and isn't ignorant of social rules, merely indifferent. He has few to no genuine relationships; he has more hopes for a meaningful connection with India that won't make him uncomfortable because he's never known anyone like himself, and hopes that she'll be a better choice of intimate. What bearing this has on the crimes he commits is probably negligible — a similar narrative of a seemingly "together" but weirdly hollow individual trying to find a family of people he can be close to could definitely happen minus the murder, but you probably wouldn't make a film about it.
- Extraordinarily acute senses — check. Extraordinarily keen reflexes as a result — check. Dark hair, blue eyes, and mysterious purpose circumventing what one might be societally expected to become? Double-check. She was found as an infant in those gorgeous fields near her home and taken in as Richard and Evelyn's own; Richard is more aware of her potential destructive capabilities, so he tries to keep everything under wraps. Perhaps her speed/strength/other Flying Brick qualities are simply being psychologically inhibited unbeknownst to her. (God knows what Charlie is.)
- My god....it all makes sense. Maybe Charlie is one of the Zod's agents that hid after the final battle?