Mama Tran is fierce. I like her a lot.

I didn't really get that this whole time Dean was trying to convince himself it wasn't his fault, rather than actually blaming Cas for letting go...which was the actual case.

Wait...I'm confused too now. I need to reconstruct this.

At the start of the season, Dean was all, "He just let go." Right? Okay, yeah, I just checked YouTube and watched that scene from the season 8 opener again. Then tonight, in the window reflection scene, Dean tells Sam he "tried so damn hard to get us the hell out of there," and he "could have pulled him [Cas] out. I just don't understand why he didn't try harder." And Sam says Dean did everything he could and Dean says yeah, but he feels like crap.

In the flashback scene where Dean, Sam, and Cas are in the Impala waiting for Mrs. Tran, Dean remembers that he lost his grip on Cas. In the resulting conversation, he asks Cas what the hell happened because it was like Cas "just gave up" and Cas kept saying all along it would never work. Dean wonders if Cas didn't trust him to actually get them through the seam, and that he did everything he could to get Cas out. When Dean tells Cas, "I did not leave you," he's blaming himself. That's why Cas is confused and asks, "You think this was your fault?" because Cas knows he chose to stay in Purgatory.

What has been happening since Dean returned is that he's been blaming himself for not doing more to save Cas, because he promised him he would. He can't understand why Cas wasn't trying harder to survive, to accept Dean's role as protector and trust him to save them both. He feels guilty because he thinks it was his responsibility to save Cas...just as it's his responsibility to save Sam, to save those who need saving, to save everyone.

Except in this case, as Cas said, "Not everything is your responsibility." When Dean says, "I don't need to feel like hell for failing you, okay? For failing you like I've failed every other godforsaken thing I care about" he honestly believes he's the one who didn't do enough to make Cas try harder to survive. So when Dean sees what really happened and not his guilt-ridden memory of what happened, Dean can't seem to believe that it was Cas who chose to stay behind on purpose because dammit, that's what Dean does, what he's supposed to do, what he's always done -- save people.

When Cas says "you can't save everyone, my friend, though you try" he's telling Dean he should feel no guilt over what happened. It was Castiel's choice. For the first time, the saving wasn't up to Dean.

Actually, in that entire last scene where Dean is putting stuff into the trunk of the Impala and starts the conversation with "That was a bonehead move back there. You could've gotten yourself killed. Why didn't you wait for me?" you could replace Cas with Sam and it would still work. Dean is taking on the parental/protector/big brother role.

Aaaand that's enough meta for one night. EEEEE, this episode.

Yeah, not really looking forward to Comic Relief Cas next week.

You officially explained that much better than the show.lol Also, Dean's brain must be a crazy place to live, that poor man.