Sneaky, sneaky Sansa (Sophie Turner).
On Sunday's Game of Thrones, when Sansa realized she and Jon didn't have enough men to launch a successful attack on the Boltons, she secretly sent a letter to an unknown person asking for help. Although the show kept the letter's exact contents and recipient from viewers, that didn't stop fans from theorizing about the big power play Sansa had put into motion.
One eagle-eyed Reddit user, ahellbornlady, posted an up-close look at the letter, which includes references to the Knights of the Vale and a promise of a deal.
Another shot of the letter appears to include the phrases "forfeit your" and "for Winterfell."
Based on this, it appears as though Sansa is writing Littlefinger (Aidan Gillen) to offer him a trade: lend the Knights of the Vale to this battle, and Sansa will give him something even better in return.
The one hitch in this theory is that Littlefinger already said he would help, so why would Sansa feel the need to offer payment for his aid now? And if Littlefinger truly is remorseful for marrying Sansa to Ramsay (Iwan Rheon), then he would still be willing to lead his men into battle to avenge her without additional incentive.
That leads us to the second option: Sansa is writing the Blackfish (Clive Russell). If Sansa could convince the Blackfish to forfeit Riverrun, then he could lead his army and take back Winterfell. She may even have a scheme to put the Knights of the Vale under the Blackfish's command in the battle. See what's happening there? It all lines up!
However, given that the Blackfish was willing to let his nephew Edmure (Tobias Menzies) die in order to keep Riverrun, we seriously doubt he'd be willing to give up the castle to go fight Sansa and Jon's (Kit Harington) battle. Plus, if Sansa were writing to the Blackfish, there's no reason for her to keep it from Jon. She has, however, already demonstrated a willingness to keep all her dealings with Littlefinger secret from her half-brother.
Who do you think Sansa is writing to?