I don't remember exactly where I've read this, but I do know he burns through bodies. Like a parasite, he must find new hosts. Evidence I do know the source for: "We came up from the dust and burrowed into flesh for warmth and became something new." "Some of these cells in this body began on this world, so strange to return." "Bodies come and go but the cells remember and if they forget the Nine remember it for us." "Some of this body's ancestors where born on this world but we were greatly changed to live in the outer worlds." In-game, just stand near/talk to him enough.