Castiel: Take me in his stead. Take me.
The Empty: You?
Castiel: I’m the one you want. I’m the one who woke you up. (The Empty lets go of Jack)
The Empty: You? But you’re already mine.
Castiel: Not for years… eons maybe. But if you’ll agree, I will go now, and I will go willingly.
The Empty: Deal. Oh, but not now. No, no, no, no, no. No, you see, I-I meant what I said. I-I want you to suffer. I want you to go back to… to your normal life and… and then forget about this and forget about me. And… And then, when you finally give yourself permission to be happy and let the sun shine on your face, that’s when I’ll come. That’s when I’ll come to drag you to nothing.
Castiel: I accept.
From Supernatural – Season 14 Episode 8: ‘Byzantium’ (14×08)