Who spoilers/MetaFilter comment

There were a lot of things in this episode that made me think there's some connection between River Song and the TARDIS matrix. She seems to know things about him that only the TARDIS knows or should/would know (including how to PROPERLY drive the TARDIS), and then, of course, there's the "romantic" connection. We've already seen Rose and Donna absorb some TARDIS energy, so it's no impossible for River to have interfaced with the TARDIS at some point. Perhaps she volunteers to "host" the TARDIS for a bit, so the Doctor can have her back for a bit.

I have my theories about the relationship between the Doctor and River. I feel like it's entirely possible that their relationship is largely imagined (by her). It's sort of like one of those things where if you say something enough it becomes true, or at least, you start to believe it? Because when the Doctor meets her, she tells him all these things about how close they are/will be, and so he's like, yeah, ok, maybe. And they're closer right off the bat because she instantly trusts him. So he's more and more intimate (or at least friendly/trusting) with her each time he sees her, which just (self-)fulfills that prophecy about them being close. I almost feel like when she realizes in the library that it's the last time she'll see him, she understands, but keeps up the act because she also understands how it must be, because, well, it's already happened. That's kinda sad in a Donna-Noble-esque way, but could be really poignant if handled well.

There were some really great character moments for the Doctor here. The bit about wanting to be forgiven, his reaction to there being other Time Lords still alive, outside the universe (and his corresponding reaction to finding out that wasn't the case), and his whole interaction with Idris. I also loved the title. Gaiman really loves to get into the guts of myths, so it's no surprise he found somewhere to explore in the Doctor's mythos that was somewhat untapped. And, of course, I know it won't put a halt to any of the shipping/speculation that goes on, but it really does explain on no uncertain terms who/what the Doctor loves.

And I think it's a good testament to the story and to Smith that it's given me insight into Ten, as well. Because man, if you think about it, Ten was really like, the Doctor's mid-life crisis. Brash, flashy, romantic relationships (flings, really) with much younger women (at the very least, Rose and the nurse from Family of Blood). A bit of a showoff, and... well, maybe not 'obsessed' with his own power, but at least interested in it. Really trying to assert himself in the face of his own (and others') mortality. The 9th Doctor was the wounded Doctor, sorta like the middle-aged guy who's just lost his parents (the Time Lords), parents he didn't get along with, and now has to deal with all that unresolved angst on top of his grief. And he has to face being alone, and mortal. Speaking as someone who's lost a parent: you feel like your parents can do ANYTHING when you're a kid. Some of that lingers even as you grow up, but harsh reality sets in when you see your mother/father wither and die. I can't imagine what it must be like when you're the one who pulled the plug/trigger. So yeah, you've got this guy confronted with his own mortality, knowing that there's a good chance his best years are now behind him, and there's no one to protect him if it all goes wrong. If that's not a recipe for a mid-life crisis, I don't know what is.

Whereas 11's faced those demons (again, Amy's Choice). He's a more mature Doctor (and I have another theory about the Doctor's regenerations getting younger because he doesn't feel the need to impress others with age; crotchety old Hartnell was just a mask, a younger man playing older to seem more mature and maybe also a bit scary). He's not quite mastered his own mortality—you never do—but he's more accepting of it. He's at least stopped completely defying it (and maybe that's part of what happens when he "dies" 200 years in the future; he actually accepts that he must die for X to happen). This is also where the bits of McCoy seep in; he's able to be a gamesman because he understands the long game more now; he's ok with setting threads up with the knowledge that only some of them will play out in the end. He doesn't need to be all dash and swashbuckling now; sure, that's still fun, but he understands that it's usually sound and fury signifying nothing. All hat, no cattle. Which is why the Stetson was kinda symbolic, I think. Sure, he still talks a lot because he's the Doctor, but underneath, this doctor is much more like a grizzled old gunslinger like Eastwood's Man with No Name, or one of Kurosawa's Seven Samurai (not Katsushiro or Kikuchiyo, more like Kambei or Kyuzo). But he's not a complete stoic (and is still vulnerable to his emotions, as Amy points out). He cares; he'll always care, and that's always been his weakness. But getting older is not about having no weaknesses (again, see above about the oooh scary Hartnell mask) but rather about accepting and acknowledging your shortcomings and learning to live with them (and hopefully finding people who can help balance them out).