One interesting theory I have is similiar to the Highlander series. Could the Losties be part of a group of Highlanders not knowing it? Richard a highlander who never ages and maybe the group of Ilana & company may be Highlanders asking the questions are these people one of us. The other theory that only Highlanders can kill Highlanders and become more imune when doing so. Richard can only be killed by another Highlander so no real threat initially and he lives quite a long time. I know my theory has holes but there may be certain Losties that have the same characters of a imortal but just don't no it. And could Highlanders produce offspring from mortals. Maybe that is why Walt and Aaron are so important because they represent more of the threat to the older imortals. And Jacob and MIB are one the original imortals that are always testing each other will. They also relize that maybe the island has somehow imp! risoned there and that there always looking to recruit other imortals ggod or bad. Well just a thought.