Ezekiel: the importance of a name
In re-watching the episodes of season 9 that have aired so far, this parallel stood out the most to me. Both times, someone else says the name Ezekiel to Castiel, but they prompt two completely different responses.
In 9x01, Dean tells Castiel that the angel helping Sam is Ezekiel, and clearly Castiel is glad to hear the name: it’s an angel he knows to be honorable and good. In fact, he trusts Ezekiel enough to leave the Winchesters in his care until he himself could find them.
In 9x09, Castiel has reached a critical point in his human experience. He’s tried to guide the angels that have crossed his path, tried to steer them away from violence and bloodshed. But again, his explanations are rebuffed and innocents are harmed and/or killed in the aftermath. Muriel’s death greatly affects him, and the conflict is clear in Castiel’s eyes: he wishes no more of his fellow angels’ blood on his hands, but it seems force is the only option left to him. The revelation that Ezekiel died in the fall seems to be the proverbial straw that finally breaks the camel’s back. After all, Castiel has been acting under the impression that Dean and Sam were being assisted by one of the few good angels remaining. Instead, he learns that some unknown angel lied in order to gain the Winchesters’ (and in turn, his) trust. Faced with all the deceit, corruption, and darkness evident, Castiel loses hope in a peaceful resolution to the problem. Instead, he must once more be the soldier, albeit a reluctant one.