Season 7 of Game of Thrones has been absolutely wild. With just a handful of episodes left before the show concludes forever, HBO has delivered a season chock full of nail biting action, long awaited reunions, and new character pairings. But one plot line that seems to be both puzzling and frustrating viewers is the current tension between Arya and Sansa Stark. The three Stark kids are back safe in Winterfell, yet Ned's daughters don't seem able to truly bury the hatchet and start an adult relationship. Their conflict will likely come to a head in this Sunday's season finale, and in my opinion there's only one way that they showrunners should handle the already controversial plot point: have them team up with Bran and get Littlefinger the hell out of Winterfell.
Of course, the editing for the past few episodes doesn't seem to be hinting at this. Arya and Sansa have been quarreling both in public and private, with their last scene happening in Arya's chambers. Sansa discovered some of Arya's faces, and the youngest Stark seemed to threaten Sansa with her valerian steel dagger, before handing it over. It seems like either of them could die in the finale, but hopefully things will actually work out.
Because Bran is also in Winterfell, and he could be the key to resolving their conflict. With Bran now transformed into the Three Eyed Raven, he's able to see the history of Westeros and is all knowing of both the past and present. As such, he should be able to figure out that Littlefinger is pitting his sisters against each other, and let them know the truth. Bran already seems to be onto Littlefinger's tricks, as he quoted a line of dialogue that Petyr and Varys shared back in the day. So if he just blows up Littlefinger's spot, then Arya and Sansa should have no reason to quarrel.
It's also a possibility that this was the plan all along. When the three Stark kids met at the Godswood a few episodes ago, they collectively discussed how Littlefinger was untrustworthy. Bran then gave Arya the dagger that was used in his assassination attempt (which helped to fuel the feud between House Lannister and House Stark), showing how he wasn't going to be manipulated by Petyr.
The three of them may have concocted a plan to manipulate Littlefinger, letting him believe he's driving a wedge between the Stark children. After all, Arya didn't even bother to conceal her identity when she broke into his quarters, which seems unlike her. Then again, Sansa and Arya's last argument was in private, so perhaps that moment was genuine after all.
Regardless, Bran needs to step up and tell his sisters to cut the shit. I'd love to see Sansa and Arya take Littlefinger out together, as punishment for the bevy of times he's betrayed House Stark. Sansa should be able to manipulate Robin Arryn in his place, and therefore keep the Vale pledged to House Stark.