Jack: Why? Why did you do that?

Castiel: Because I made a promise. Because I love you, Jack. And Sam and Dean... they love you. And they are fighting for you at this very minute. I hope that... They don't need to know what happened here. What I did... I'm... I'm... I'm at peace with my choice. I don't want them to worry.

Jack: I won't tell them. I promise.