Oh my god...That charlie is compromised is the most ridiculous one yet. Not everything can be weird or strange on the island--the best part of Lost is that there are a few explanations for many strange goings-on. For the show to be good, Charlie doesn't need to be an alien or compromised.

I do agree that Charlie didn't quite act at the end as someone who's just been through a traumatic experience, perhaps a bit of bad writing. Or maybe good writing--he's just been through a traumatic experience and he's been greeted with open arms by Claire. Why not be happy?