[EVERYTHING] Arya's speech to Sansa

At first, I interpreted Arya's "I steal faces" routine as a threat. The show is clearly playing up this Arya/Sansa feud to worry us about Winterfell and show us how clever and tricky Littlefinger is supposed to be. But I'm hoping against hope that Arya is finally the character we need, after six/seven seasons of getting there.

Like Littlefinger, the writers of the show like to obscure plots. They promise us one thing (trial by combat!) and then give us another thing (a dumb septon trial instead, lol!). Arya is telling Sansa, "Hey. I could kill you and steal your face. Here's a dagger instead". Is it just a cocky little girl threatening her sister? Or is she telling her that she's safe, at least for now?

And more importantly, whose face is she going to steal? It can't be Sansa, that's too obvious. So either she's going to replace someone like Wolkan in order to get unfettered access to Sansa and Littlefinger, or she's going to give us what we have all wanted since the first season and she's going to kill Littlefinger. How great would it be to have Littlefinger smugly walking around all episode only for him to pull his face off at a pivotal moment and be Arya? We already saw it coming with Walder Frey at the beginning of the season. This time it would be a nice little surprise for the finale.