Castiel: Everything you have ever done, the good and the bad, you have done for love. You raised your little brother for love. You fought for this whole world for love. That is who you are. You’re the most caring man on Earth. You are the most selfless, loving human being I will ever know. You know, ever since we met and ever since I pulled you out of Hell, knowing you has changed me. Because you cared, I cared. I cared about you. I cared about Sam. I cared about Jack. I cared about the whole world because of you. You changed me, Dean.
Dean Winchester: Why does this sound like a goodbye?
Castiel: Because it is. I love you.
Dean Winchester: Don’t do this, Cas. (The Empty shows up) Cas.
Castiel: Goodbye, Dean.
(The Empty takes Cas and Billie along with him…)
From Supernatural – Season 15 Episode 18: ‘Despair’ (15×18) | Produced by The CW