[That makes him think of poor Amy, dead and undead and then somehow alive, all only to be dead again.

Or of himself, the far more typical case: the most alive now that he's ever truly felt, but undead to the rest of the world, and dead forever to his father.]

Changed is only the same as gone to those who fear change in the first place. That's a symptom more common to the living than to the Partially Deceased.