That he had just had enough and was probably suffering from horrific PTSD after everything that he had been through. That he regressed into a somewhat childlike state to protect himself from his own awful memories, pain and guilt at everything he had done. But he wasn’t crazy.
I think this exchange was wonderful:
CASTIEL: You seem troubled. Of 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? You’re worried about the burden I lifted from you.
SAM: I think 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… 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, Cas, and I’m grateful. We’re all grateful. And we’re gonna help you get better, okay? No matter what it takes.
CASTIEL: What do you mean, “better”?
Cas was trying to recover from his trauma. He went about it in an odd way, but it was all about avoiding violence and finding peace - whilst running from the things he couldn’t cope with. He was well aware of his surroundings, and the situation, including the seriousness of the situation with the leviathan. He just didn’t want to deal with it because he physically COULDN’T because he was still far too traumatised. Note that he asked Sam what he meant? Cas certainly didn’t think he was crazy at the time or that he needed to get better.
There is a lot of wank about Cas going around at the moment, and people saying that he isn’t the bad ass mother fucker he used to be and how that is making them angry, how he is #notmycas anymore. But I need to point those people to the version of Cas we call “crazy cas” and ask them to really look and assess the situation. Cas had to do awful things in season 6, the war in heaven changed him, made him power hungry, he was manipulated by Crowley and forced to do things he never would have done otherwise based on the situation Raphael put him in. When I see people using season 6 as an example of the version of Cas they miss, I get really fucking sad. Cas hated who he was in that season, and he has spent every season since trying to repent for his actions.
Crazy!Cas is the result of this story. It’s not about Sam’s hallucifer visions. Cas says it himself above, he didn’t see Lucifer after the residual from Sam’s “crazy” had passed. For Cas in that state, it was always about finally seeing the bigger picture, clearing his head and deciding nope, I don’t want to fight. I don’t want to be a bad ass mother fucker.
The fighting is what broke Cas. He was terrified of further conflict, and every time even the idea of him getting involved in the fight again in 7x23 came up he would change the topic to something seemingly crazy, like wanting a cat or playing twister. He wasn’t crazy. He was playing crazy. He had no confidence in himself, or belief in himself, and that was what really held him back, but it was due to his trauma, his PTSD that caused the regression.
I loved Crazy!Cas so much because of just how important it was for Cas’s eventual recovery. You’ll note that when duty did call, he stepped up, he helped Dean to find Dick Roman, and he resorted back to violence when Dean’s life was in danger. Because even when he desperately wants to avoid violence, he will still risk his life for Dean. It fucking hurts but its the truth. After the talk with Dean by the Impala, Cas no longer appears crazy. He decides to go with Dean. Because Dean “would rather have [him] cursed or not.” and it was enough to get Cas to join the fight. But that doesn’t mean it was a good thing at all, and the following season explored how Cas’s devotion to Dean was used against him with horrific consequences, but that’s a topic for another day.
Look it isn’t surprising that so many people in fandom have latched on to this idea that Cas is obsessed with bees, and flowers, and nice natural things. It all comes from THIS version of Cas, because this was Cas’s regressed state. It was him ignoring duty, and obligation to heaven or the Winchesters, and just being. It wasn’t great for his mental health as it was all about running away, but these are things that Cas actively chose for himself. He wasn’t crazy, he just wanted some damn peace for once.
I’m in love with a boy who likes Norah Jones songs, who tries to draw his favourite Van Gogh’s paintings, who wanted to sing with Whitney Houston when was asked about his dreamed collaboration and has a beautiful deep voice which melts my heart.