Coulson is Fenrir. I don't know if Clint knows. Clint's badly hurt, I think it's possibly an explosion, building collapsed? And Coulson just starts to flip out and Loki appears, I think to calm him down and assist where he can. I don't remember if this has Jormangandr!Fury or not, because the focus for me was Clint/Coulson.
While I'm at it, if anyone has any good Fenrir!Coulson/Clint recs, I'm all for them. Notoriously hard to squick, so any kink, any type, welcome.