Dumah: If we had him, he wouldn't be imprisoned. He would be put to work.
Castiel: What do you mean?
Dumah: Castiel, the angels... Our numbers were greatly diminished after the fall. No one's made new angels since the dawn of creation. We're going extinct. You would need a powerful force to make more of us.
Lucifer: I got plenty of gripes with the old man. His self-righteous narcissism, his “my way or the highway” quirk. I gotta hand it to him. He had a couple of great seconds when he banged out the universe. Guy had creative chops. And optimism. I'll give him that. And despite his pissiness and his massive lack of irony, he did give mankind a good turn at bat and a chance to live in paradise. He ruled. He smote. He parted waters. Worshipped by creatures who made God in man's image. And then, he got disappointed. Or worse, bored. Picked up all his toys and... left.
Castiel: Jack, I've killed people who didn't deserve it... my friends... I've killed people I loved. I wish I could tell you that it... that it gets easier, that with time, it hurts less, but that would be a lie because it... it never gets easier. And those moments, they never stop hurting. But that doesn't mean that you should stop fighting. Doesn't mean that just because you made a mistake... and that's what this is, Jack. It's a mistake. That doesn't mean that you can't... can't be better, do better. I believe that. I have to believe that.