Arya is filching tarts from Hot Pie when Vargo Hoat comes back with prisoners, and they're Roose Bolton's men. This is a bit of a worry, so when she sees Jaqen next she asks him to help her free the prisoners so they can take over Harrenhal. Pretty impressive for a ten-year-old.
He says no, so Arya asks him to kill himself as her third wish. He hesitates and she says if he helps her then she'll change the name. This is a stunning bit of chutzpah. Arya really is playing with fire: here's a sorcerer who can make dogs chew men's faces off and she's tricked him into doing her bidding. Which is bound to piss him off and once his debt is repaid he'll be presumably free to put a hex on Arya for her cheek.
For now it works, though, and Jaqen has Arya order a vat of hot broth from the kitchen which Jaqen and his men pour over the guards, freeing the prisoners. But it turns out that Vargo Hoat was working with the Roose Bolton all along. The prisoners aren't prisoners at all, they're not injured. Bolton duly takes over the castle.
All of which leaves me wondering what Arya has achieved, save using up he last wish and being promoted to Bolton's personal wine-pourer. I'm not quite sure why she hasn't revealed her true identity to Bolton, but going home to Winterfell might not be a great idea right now anyway.
Jaqen changes his appearance in front of Arya's eyes before making his getaway (and giving her a secret coin and secret password to find him again). The list of characters who have directly witnessed magic happening is growing.
