Oh man, either that one or #24, both of which went super fast. Looking up the lyrics to the Nico song was the thing that gave me the idea though, that Dean had been acting like a soulless bastard during 2014 because that's what he was - that at some point early on he decided that he'd be able to make the tough decisions and be a better leader without his soul getting in the way and found away to manage that. And then Lucifer brings him back from the dead soul intact and Dean starts getting flashbacks of everything he did.

(The one I'm already working on is a post-"On the Head of a Pin" AU were things don't end quite so well.)