spoiler: that nathan guy

so at the very end we see that saya kills him at his own request but he appears later on. now, i remember when he told amshel that he'd been around even since before, leading me to think that he was saya and diva's mother's chevalier, so then saya's blood wouldn't kill him at all making him live forever unless someone cuts his head or burns him (like amshel explains is the way to kill a chevalier). so is that it? was he their mother and not diva's chevalier?