1. There's a post on Tumblr about the parallels between Mary going to AU Land and Dean going to Purgatory. And the more I think about it, the more annoyed I get. Because yes, there are significant parallels.
Dean gets zapped to Purgatory. Sam assumes he's dead. Sam has no reason to think he's alive - after all, the explosion that sent him there killed Dick Roman, so why would Dean have survived it? Why would Sam suspect he's in Purgatory? So Sam doesn't look for him, and the Show, and Dean, and a certain subsection of the fandom, never get over it.
Mary gets zapped to Purgatory. Dean assumes she's dead. Dean knows exactly where she went, because he went there too. He knows the trip didn't kill her, he knows without a doubt it's possible to survive there, and given his lifetime of experience, he knows that if a door was opened once, it can be opened again. But he doesn't look for Mary, because he's convinced she's dead. Is anyone up in arms over it? Are the fans saying how dare Dean not look for his mother, because you don't abandon family, no matter what? No. They are (quite rationally) saying yeah, Dean's fucked up, I can understand why he'd give up. And I don't disagree with that. But I do find it hypocritical to still blame Sam for not trying to get Dean out of the place he didn't even know where he was, and yet cut Dean this much slack for deciding Lucifer must have killed Mary and dropping the whole thing. And I'm pretty sure the Show isn't going to have Dean apologize, several seasons later, for not trying to rescue her.
B. In the comments on my initial review, xparrot pointed out the potential significance of Dean telling Jack that if he's going to be killed, Dean will be the one to do it, not Sam. That this could be his way of supporting Sam as much as possible - by admitting it's an "if" and not a "when," and by letting Jack know that Sam won't be the one to kill him if it's necessary. And that made me think, what if this is Dean's way of protecting Sam? If he feels Jack is dangerous, and there's a chance he'll kill anyone he finds threatening, Dean wants to make sure he's the one in Jack's sights, not Sam. And then I had to sit down and pet a dog until I felt better.
Third. In the comments on the 13.02 poll, jj1564 put forth the theory that most of the women are missing from AU Land because the angels took them to heaven to make nephilim to win the war. Which I find brilliant. And it's so rapey that I can't believe Buckleming didn't come up with it on their own.
Actually, there's a lot of brilliant comments on that poll. Because y'all are brilliant and observant and clever, and I love you all.