Castiel and Sam in “Unfinished Business”

Castiel

You seem troubled. Course that's a primary aspect of your personality, so I sometimes ignore it.

Sam

Okay. Um... right now I'm just wondering about you.

Castiel

What about me?.. [realizes] You're worried about the burden I lifted from you.

Sam

I thought I was done for... Do you see Lucifer?

Castiel

I did at first. But that was... It was a projection of yours, I think, sort of an aftertaste. Now I more see... Well, everything. It's funny. I was.. I was done for too. The weight of all my mistakes, all those lives and souls lost, I...I couldn't take it either. I was... [Sighs] ..I was lost.. until I took on your pain. It's strange to think that, that helped.. But-

Sam

I know you never did anything but try to help. I realize that, Cass, and I'm grateful. We're all grateful. And we're gonna help you get better, okay? No matter what it takes.