I've been thinking a lot about Mary's actions this season, particularly in 12.12. I came down pretty hard on her, but some Tumblr conversations have got me rethinking things.
One thing we know canonically about Mary (until someone chooses to retcon it away) is that she hated the hunting life and was determined not to raise her children in it. So she comes down from Heaven and finds that the husband she just left is dead, and her two beloved babies are grown and hardened and broken, all from hunting. Everyone she loves has been destroyed by monsters.
And then Mick Davies sits across from her and tells her to imagine a world where no one dies because of monsters. No wonder she's interested. No wonder she's hunting again.
So, I don't know exactly what she's planning to do with the Colt.
fanspired theorized in the comments on
this post that she's (or the BMoL? I'm still not quite sure who kept it, but now I think Mary did) not planning on using it to kill monsters one-by-one; there's some big plan in the works and the Colt is part of it. And after all, it was the key to a portal to Hell, so there's no reason it couldn't be instrumental in some other way.
But then why work with the BMoL secretly? Why lie to Sam and Dean about it instead of trying to convince them to work with her? The theory goes that she knows they'll oppose her. Dean even said, in the diner, that he doesn't trust them. So if this is her "closing the gates of Hell" moment, and she thinks they might try to stop her (because her plan will result in her death?), she's not going to reveal it to them.
And why would she trust the BMoL, given what they did to Sam and Dean? Because as far as she knows, Toni Bevell was working completely on her own, was punished for her actions, and sent home in disgrace. She doesn't know Toni has the same hidden agenda as the rest of the BMoL.
The problem with this theory is that (a) Sam and Dean have already worked with the BMoL, when they cast Lucifer out of the President, and (b) Sam and Dean already know Mary called the BMoL for help when they were roaming the woods of Colorado. Now, she may not know about (a), but she was definitely there for (b), and while Dean wasn't pleased to see the hobbits, he didn't bitch at her and warn her never, ever to work with them again (and considering that he thought he was about to die, if this was on his mind, he would have made a point of saying it while he had a chance).
However, if she thinks they'll object only to the Grand Plan, and not to the fact that she's working with the BMoL to achieve it, then things start to fall into place. Successfully completing the plan will eliminate monsters but also have some fallout she knows they'll find unacceptable (again, probably her own death), and so the questions she was afraid they'd ask weren't "why would you work with the BMoL" but "what exactly are you working on?"
Now, I'm still disturbed that she values the Grand Plan not only above her own life, but above Sam and Dean's as well, since she refused to hand over the Colt when Ramiel demanded it.
junkerin hypothesized in the comments on the
12.12 poll that Mary was about to hand it over, but Dean beat her to it. And maybe that was the case. Or maybe ridding the world of monsters is so important that she's willing to sacrifice the lives of these two men who she doesn't really know all that well anyway. And she knows Heaven is a better place to be, so. Yeah. Maybe. It's a mercenary act, but it fits with what we know about her. She made a deal with the yellow-eyed demon to save John, not even asking what she was trading away. Her father was a very ends-justify-the-means type of hunter, at least in his second go-around on Earth, and there's no reason she couldn't be the same way.
Anyway. I'm not 100% committed to this theory, but it does make sense of some things that need making sense of. What do you think? (And as aways, no spoilers in the comments please!)