Castiel: I told you, war is coming. War. And I did what soldiers do. Now we needed the spell to open the rift, and I got it. We need four major ingredients... the grace of an archangel... a fruit from the Tree of Life... the Seal of Solomon... and the blood of “a most holy man.” We find those things, we can bring everybody home. And together, we can beat Lucifer and Michael. This is the only way we win, and this is the only way we survive. It's like you said, Dean. Whatever it takes.
Dean Winchester: Jack brought you back because we needed you back.
Castiel: Right. And how have I repaid him? I promised his mother that I would protect him, but now he's trapped in that place while Lucifer is here, who's... I mean, he's getting stronger and more powerful by the day. And if Michael really is coming, maybe I was brought back to help prepare.
Dean Winchester: Prepare for what?
Castiel: War. War is what Michael does.
Dean Winchester: Well, then we do what we do. Whatever it takes.
Castiel: Stop. I don't wanna hear any more of your lies.
Lucifer: Oh, this coming from the angel who almost has me beat in that department, and that's saying a lot, pal.
Castiel: Well, you always say a lot.
Lucifer: Okay, let's face it, Cassandra, the truths I say hurt 'cause they're hard to swallow, so people call 'em lies. Go figure.
Lucifer: Well, if somebody would be a pal and let me eat a little of his grace, I would have enough strength to get out of here and butcher that son of a b*tch!
Castiel: Well, that's a nice, horrifying plan. Little cannibalism.
Lucifer: Really? I seem to remember a somebody snacking on angel grace once upon a time. There is no “I” in “team”, Castiel. I want you to remember that.