I am looking for a fic that I have the urge to read but cannot for the life of me find. I've gone through my bookmarks and saved lists, but I haven't found what I think I'm looking for.

It was a Castiel/Dean story where they had come up with an alternate way to stop the apocalypse. I know they get rest of the Angel Squad on board, because Dean spends various battles possessed by Michael (who has done an about face on previous stances and is now a friend of Dean and Castiel). Michael, however, does not possess Dean all the time, and the rest of the time he wears Dean's former aunt (she had been John's sister, and had been braindead in a hospital due to an accident, I think). They also get the Vatican on board to help stop the apocalypse, as Dean and various angels make several trips to Europe to meet with people snd collect things. I believe it was posted to Archive of our Own, but I'm not sure.

This sound familiar to anyone?