I'm doing a rewatch of my own, and I just watched season 1's episode "Walkabout." I noticed when Jack sees his father in the distance, and runs after him, he instead finds Locke carrying in the boar. I don't know if this means that at this point the monster is controlling Locke's body (as some people have theorized based on evidence from Season 5 concerning the episode "Dead is "Dead" where Ben says, concerning the monster, "What's about to come out of the jungle is something I can't control", and when Locke disappears under the temple, that's when Ben encounters the Monster.) A lot of people, including me, have theorized that the appearances of Christian Shephard on the Island were due to the Monster and Jacob's nemesis. So is this foreshadowing the role Locke will have in the Nemesis' plan to use him as his loophole? I think the connection seems strong enough.