Wow, I think there’s a whole lot of over-thinking about Arya - especially at that BuzzFeed link. I’m willing to bet that Arya was stabbed once in a non-fatal place (the first stab looked off to the side quite a bit), and the second stab hit her money and the dagger got stuck. That’s why the waif was twisting it, trying to push it through. That gave Arya the opportunity to get away.
In the next episode we’ll see her passing out, then waking up looking into the face of someone we know, who will take her in and fix her up. Then she’ll go and kill the waif, and get back to Westeros. That’s my guess, anyway. I don’t think it’s much more convoluted than that.
As for Jaime’s motivations and future actions… I think he’s going to ally himself with the Blackfish and the North in the battle for Winterfell. There are lots of reasons for this: First of all, he’s a smart man, and he will listen to what Brienne has to tell him about what’s going on at the wall. Second, he has to know that Ramsay Bolton is a disaster. It’s one thing for the Lannisters to ally with Roose Bolton, who was certainly ruthless but also knew when to reign it in to keep the support of the people he needed. Ramsay is a disaster who will eventually lose the North to someone else, and the Lannisters wouldn’t want to be on the wrong side of that. Finally, if Jaime can be convinced about the threat of the White Walkers, it pretty much renders the Game of Thrones moot for the time being.
Also, Jaime has just been stripped of his honor and his life-long position by his own family, and essentially exiled from King’s Landing. He knows that Cersei is in big trouble and that the Lannisters are holding on by a thread. Therefore, regaining some form of alliance with a Stark in the North might be a big deal.
I think Brienne is going to make all the difference. When she shows up on the side of the Blackfish, it’s going to cause Jaime to do a lot of very hard thinking about his own honor and what kind of person he wants to be. He’s going to take a hard look at the band of cowards and cutthroats he’s currently ‘allied’ with, and compare them to the honorable people on the other side, and he won’t like the comparison.
This seems to me to be almost telegraphed by the over-the-top incompetence and nastiness of the Frey army. The director seems to be going to great pains to show just how dishonorable Jaime’s side is compared to the Blackfish.
And of course, it certainly looked like the Blackfish convinced him that a siege of the castle is a very dicey proposition, what with winter coming and the castle set up for the long haul. So he may not have any choice but to make peace in the first place.