Jacob^^
He could be Locke, an older version. Locke does seem to be the key in all of this (locke = lock // unlock the secrets on the island an' all that shit!)) and time travel has already been explored with Desmond, so who knows. I mean, he could just be sitting there cos he's paralyzed again. He does ask for help.
Remember when Makhail was talking to Sayid, Kate, and Locke in the woods....and he was telling how horrible Sayid and Kate really where.... then stopped at Locke and said "the John Locke I knew..." and then got cut off......Mmmm
Love this show!