Castiel wasn't going to leave Dean. He'd sooner cut off his wings, at this point. Trying to convince Dean of that would probably take him until Dean's dying day, but he would keep up the effort anyways. He would point out, as well, that they lost one another just to be found again. Consistently.
He nods his head head briefly in agreement. Somberness etching across his sharp jaw, and face. Dean was right, of course, because once they left here ... Jo would be gone. And none of them knew what had happened to Meg. She had simply disappeared as they had, or at least that was what Sam had said. "I am still not sure what that is, Dean, but I will ... I will do the best I can, by all of us."
He dipped his head again, letting Dean's hand share warmth with his, his smile tilting up briefly at the corners. The one that only belonged to Dean, because he was the one who had earned it, all those years ago. "I know. You and I, at the end of the world, with Sam. There is something to be said ... about fate repeating itself."
He dipped his head once, in acknowledgement of everything neither one of them could say, before he disappeared without another word.