LOCKE

So, this isn't really my theory. My in-laws' friend Holly presented this in an email chain today, but I think it's a pretty good idea.

Remember last season when crazy Hurley told Jack that Charlie had a message for him? Charlie's message was, "You're not supposed to raise him, Jack." At the time, I think most people assumed that this meant Jack was not supposed to raise Aaron. Similarly, when Claire visited Kate's house and told Kate not to bring "him" back to the island, it was assumed that Claire meant Aaron.

But I think that both Charlie and Claire were referring to Locke.

With all of the ambiguity surrounding Locke's death and Ben's insistence on preserving Locke's body, I think there is a good chance that Locke could come back from the dead upon return to the island. I think Claire warned Kate about bringing Locke back to the island, and Charlie was really saying, "You're not supposed to raise him from the dead."