Ever wonder why Claire asked Kate to never bring Aaron back to the island?
In Season 5, Ilana recognized that Jacob's cabin had not been inhabited by Jacob in quite a while-- that "someone else" had been using it. In that cabin, we earlier saw Christian Shephard, the first corpse to arrive on the island and become reanimated by Jacob's nemesis. With Christian, we saw Claire, who was obviously very comfortable in that scenario.
So if Claire is being influenced by Jacob's dark-haired nemesis, there is a serious probablity that her request for Aaron to never return to the island was due to the fact that Aaron has a very special purpose.
I contend that in the upcoming season, we will discover that Aaron is the son of Claire and Jacob. The reason Claire does not want Aaron back on the island is because she knows that with Jacob dead, his son will be the heir-apparent, and foil the plans for control, prepetrated by Christian/Flocke/Jacob's nemesis.
(Its a stretch, but not out of the realm of LOSTibility)