As Jon Snow and Sansa Stark gathered troops before marching on Winterfell, it became quickly apparent that the Northern allies didn’t have enough support. So, behind Jon’s back, Sansa took matters into her own hands by sending out a mysterious letter. While the show didn’t explicitly say who that letter was to, some Reddit sleuthing has potentially revealed the answer.
Note that there are spoilers ahead.
After rallying support for their cause, Jon and Sansa butt heads over the fact that they don’t have an army big enough to take Winterfell back from the Boltons. On the one hand, Jon knows they don’t have a big enough army; on the other, Sansa knows they must march now or else a winter storm could foil their attempt. It’s a bit of a Catch-22; either way, they must attack Winterfell—and soon.
This is when Sansa writes her letter, but to whom? Well, based on a previous exchange between Sansa and Petyr Baelish, it’s pretty safe to assume that’s who the letter is to, especially considering he previously offered aid. According to some screen grabs and after filling in the blanks, here’s what the letter might’ve said.
You [promised] to protect me. Now you have [a chance] to fulfill your [promise]. [Knights] of the Vale are under your command. Ride [north] for Winterfell. [Lend] us your aid and I shall see to it that you are [well rewarded].
Of course, this is based on obscure images that only partially reveal her letter, which we have to assume is to Littlefinger. Based on her concern for Jon’s small army and Littlefinger’s promise of aid, there’s only on logical answer.
I’m guessing the letter will reach Littlefinger just before Jon and his army begin their siege on Winterfell, and come to their aid just in the nick of time. There are only three episodes left in this season and Jon’s march on Winterfell is just one of many big storylines we’re still waiting to tie up.