I have a feeling that Jack is going to end up killing someone in the season finale to secure them(the Oceanic 6) getting off the island, and it just might be one of the other Lostie's. Let me explain. In Through The Looking Glass, when Jack sees the obituary he is overcome by grief. In my opinion, it is Michael in the coffin. Michael was not able to kill himself until he finished what the island needed him for. The first thing Jack tries to do is kill himself after reading the obituary. Right before he is about to jump off the bridge, a car crashes and Jack has to save the woman and her son. It wasn't quite like Michael's gun not going off, but there are similarities. The producers said that we would get insight in Meet Kevin Johnson into why Jack wasn't able to jump off the bridge. If we are to believe that it is the same thing(the island not letting them die until they finish something), then I will take it one step further. Michael ! killed Ana-Lucia and Libby to get his son back and get off the island and his off island experience afterward appeared to be pretty rough. It was the same with Jack. I think that in the season finale, a situation is going to present itself to Jack where he can secure at least some of the people to get off the island and he is going to have to kill someone to do it. I think the strongest possibility is Juliet. I'm still not sure who is the one to get the six off the island(Ben or Widmore) but it will be for one of those people that Jack will do this for. I just keep thinking about how Hurley said to Jack in the season premiere that he should of went with Jack and he made a mistake by going with Locke. I think he says this to Jack beause he is afraid of Jack to an extent. He might even be thinking that Jack is working for whoever gets them off the island. Also is Yi Jeon, when Hurley is happy that no one else is coming to see the baby. He probably knows about what Sa! yid is doing and isn't happy that Kate has Aaron and is still ! upset wi th how they left the island and what Jack did. I know this was long-winded and possibly a little far-fetched, and it takes theories from other people(as far as Michael being in the coffin and Jack having the same experiences as him off the island), but I like to think I'm taking those theories and my own and making an even bigger theory.
Theory by Brianamolsch
Theory by Brianamolsch