If you're smart, you don't bet against Littlefinger, even in the most testing of circumstances.
There's a reason Bran gave Arya that dagger, after all.
And if you haven't already guessed, the remainder of this article will contain major, wide-open spoilers for the most recent episode of Game of Thrones, and from an earlier episode, and possible future episodes.
Unfortunately for Sansa, that survival technique, which was somewhat rooted in an idealism that blinded her from the truth - and which is far removed from what she is now (pragmatic, regal almost) - has come back to haunt her in he shape of the scroll Littlefinger enabled Arya to find.
But Arya and Sansa don't know what impact the letter might have had.
A central character for three seasons, she was murdered alongside son Robb and his heavily pregnant wife Talisa during the show's most notorious episode, The Rains of Castamere, famously known amongst fans as "The Red Wedding" due to their brutal end. Father has been charged with treason.
So back to what it says: upon pausing the scene, we can decipher the words "killed from wounds", "Joffrey", "tried to steal his throne", "King Joffrey", and "Your faithful sister Sansa". The Lannisters are treating me very well and providing me with every comfort. I beg you: come to King's Landing, swear fealty to King Joffrey and prevent any strife between the great houses of Lannister and Stark.
I'm not going to pretend to know the specifics of Littlefinger's plan, but we can see something taking shape here.More news: Pantone announces color to honor Prince
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After the Lannisters conspire to have Ned Stark declared a traitor, Littlefinger says that "a girl is innocent your grace, she should be given a chance to prove her loyalty".
What we're seeing now - six seasons later - is the note that Sansa ended up sending to Robb.
See? Sansa was totally coerced. Hopefully she'll figure it out though, considering Robb and Maester Luwin did pretty much immediately.
Littlefinger knows that Sansa is his key to keeping his hopes of possibly sitting on the Iron Throne alive.
Rather than swear loyalty to Joffrey, Robb chose to call his their bannermen and urge them to stand alongside with House Stark in rebellion against the Lannisters. If there's chaos in Wintefell, he can use that to "climb the ladder" to... well, who knows what Littlefinger wants. It's hard to read and purposely out of focus but here's the gist: it's a letter that highlights past family betrayals by Sansa. "She hasn't dealt with Littlefinger for a while so she gets roped into spying on somebody who is actually leading her by the nose to something that he wants her to have". Sansa Stark was on the wrong side of all those moments, which cause the gears to start turning in the head of Arya.
You can see the full discussion below. And its contents confirm that Littlefinger is conniving to turn the Stark sisters against each other.
We'll have to wait until season 7 episode 6 to find out.