Charlie is a great character but he has done had a few stuff ups though like when he took Claires baby hid the statues full of heroin and he was also the one who knocked Sun unconcious.
I think he is one of the better actors on Lost
You see in flashbacks his brother forcing it onto him or pushing him to go down that path.
Charlie was fine until they found the plane full of drugs....it was those damn statues that made them think he was using again and make him want to go back down that path again.
I love Charlie so much... but I'm so worried about him! I feel so sorry for him and so angry at Locke for hitting him... but I still like Locke. Charlie rules!