I don't do anything on this wiki really, as I'm too busy on other wikis, but I have a theory that I strongly consider you read and think about. Here it goes. I think that The Man In Black and Jacob are both the same person, from different timelines. You see, I think that both of them are Aaron. I think that The Man In Black couldn't kill Jacob, because they are the same person, but he could let someone else do it. When Juliet said, "It worked," I think she was referring to the Flash-Sideways Timeline, which they never crashed on the island. Here's my explanation for the "Two Aarons" that I think are The Man In Black and Jacob. The Man In Black is Aaron from the timeline where they crashed on the island. You see, I think that Claire's baby did die when they crashed, and that The Man In Black took the baby's corpse. Claire did not raise this Aaron, so he grew up to become evil, as he was The Man In Black. For the other Aaron. This Aaron comes from the Flash-Sideways timeline, where they never crashed and Aaron didn't die in his mothers belly. This Aaron will be raised by Claire, I predict, and will somehow go back in time to the island. Aaron will go by an alias, as we all know Jacob, and will protect the island from Aaron's bad self. I think that the good Aaron changed his name to Jacob because he didn't want to let people know who he really is. In conclusion, I mostly think that the island is symbolic of Aaron's conscience. What do you think?