Unlike their younger brother Bran, who has secluded himself in the forest and distanced himself from the Stark name, Sansa and Arya are still proud Starks - they just don't know what that means anymore. Arya and Sansa Stark need to stop engaging in a cold war against one another and start working together, even if they are justified in their respective suspicions of each other. In a meticulously detailed theory, the user suggests Arya is intentionally acting antagonistic so Littlefinger thinks she and Sansa are on the outs-but in reality she's had her sister's back this entire time. Arya would believe that Sansa truly turned her back on the family. What should have been a joyous reunion has become a new period of uncertainty in Winterfell. They should be able to trust each other, but instead Arya and Sansa are locked in a frustrating dance of sibling rivalry orchestrated by Littlefinger.
For example, in Sunday's "Beyond the Wall", the mistrust that began to take shape in the previous hour as Arya questioned Sansa's rule of Winterfell in Jon's (Kit Harington) absence continued to build. What else are they supposed to do, when there's less than ten episodes ever, and so many storylines to resolve?
After all, a girl is Arya Stark of Winterfell and she IS home. That seems wrong. She feels under threat so she sends away her bodyguard? Even if that rest only lasted for a few minutes before the Night King had his frozen flunkies drag you out of the water (where did they get those chains, btw?). Over at the Los Angeles Review of Books, Aaron Bady writes that the "Sansa and Arya thing... requires them both to be maximally petty and mean and lacking in insight or compassion", while Sarah Mesle sees in the sisters acting "as the worst and most reductive versions of themselves" evidence that women's "fears and anxieties are not, for the writers' room of Thrones a source of sympathy or heroism", particularly contrasted with the naked fan service north of the wall.
The theory brings to light how Arya and Sansa, through the seasons, have suffered enough to see through Littlefinger's cunning.
We could hope that Arya and Sansa would be ennobled by their mutual experience of trauma and band together to fight the greater evil. After being brutalized by both Cersei Lannister and Ramsey Bolton, Sansa has finally come into her own as player rather than a pawn in the game of thrones.
Arya's intentions are just as mysterious as Littlefinger's.
And then there's the freaky character assassination the show seems to be engaged in on Arya's part. She probably should have told Jon that she'd arranged for the Knights of the Vale to back him up during the Battle of the Bastards, and, as Arya pointed out, she's often defensive when she should be offensive. She is loyal to her family and always will be. Does she have any idea how bad an idea that is? This is, of course, the least generous reading of that scroll possible, but we knew that was coming too. So far this season, we've seen some not-so-subtle references to Cersei's influence over Sansa, from hairstyle to Sansa's reluctantly admiration of aspects of Cersei's leadership. She could have given herself over to the same single-minded vengeance as her mother, Catelyn. It's not just a lazy storytelling decision, but one that fundamentally misunderstands why she's remained compelling for so long: because there's a core of humanity underneath all that murderous list-making, not in spite of it. Still, she is stuck in the past, not looking at what is happening at the moment, not looking at the changes, born of suffering, written on Sansa's face. It seems unlikely that Arya's true intent was to kill Sansa.