I just recently found out about the Mobisodes...yeah, I know lol
In Mobisode 13, we see that right after the plane crash, Vincent runs up to Jack's father, who should be dead in a coffin somewhere on the island, and is told by the man to go wake up Jack because he has work to do.
So, I'm thinking that Jacob is using Christian's body for physical interaction (or for kicks?) Maybe Jacob/Christian became biased towards Claire (and Aaron) because of their relation and that is why Claire is hanging out in the cabin waiting for Aaron's return.
Since Jacob can only be seen/heard by Ben, Locke, Hurley, and Richard (I may have that wrong, though), he's using the body of Christian to be more approachable by the Losties. Or, like I said, he's using Christian for kicks and can not wait to see Jack's face when Jack see's his father and Claire lol
(Is it assumed that off-island-Jack knows that Aaron is his nephew? Seems like last season that was hinted at by Jack in the flash forwards)
Oh! Either I read it here or elsewhere, but anyone else trying to connect the dots between speaking latin, the four toed statue, and Richard being ageless?
Perhaps the island is some kind of variant of Atlantis (ancient civilization) and has a sort of fountain of youth is on the island. Perhaps that is why Widmore wants it back and why Richard never ages.
Suddenly, my brain is hurting.