Dean and Sam in “Unfinished Business”

Dean

Well, I dunno when it happened. Maybe when I was in Hell. Maybe when I was starin' right at you. But the Sam I knew; he's gone.

Sam

That so.

Dean

And it's not the demon blood or the psychic crap... it's the little stuff. The lies. The secrets.

Sam

Oh yeah, what secrets?

Dean

Your phone calls to Ruby, for one.

Sam

So I need your say-so to make a phone call?

Dean

That's the point. You're hiding things from me. What else aren't you telling me?

Sam

None of your business.

Dean

See what I mean? We used to be in this together. We used to have each other's backs!

Sam

Okay, fine, you wanna know why I didn't tell you about Ruby? And how we're hunting down Lilith? Because you're too weak to go after her, Dean. You're holding me back. I'm a better hunter than you are. Stronger, smarter; I can take out demons you're too scared to go near.

Dean

That's crap.

Sam

You're too busy sitting around feeling sorry for yourself, whining about all the souls you tortured in Hell, boo-hoo. [The brothers start to fight] You're not standin' in my way, anymore!