"He's a demon. He was supposed to tempt human souls to hell." The Soldier pauses, then adds before Sora can say anything, "Apparently he was always very bad at it. He got fond of humans. And of Aziraphale, who is an angel." There you go, Sora, there's the informational bomb everyone's been avoiding telling you. Sorry for all the secrecy, the other two are still a bit dumb about it.