Season 7 script reveals Sansa was jealous of the bonding between Arya and Brienne

The Sansa Question—What Did She Know and When Did She Know It?: Both Sansa haters and lovers alike had some difficulty puzzling out the Stark sister dynamics in Season 7. Arya and Sansa were at each other’s throats; the elder sister was inexcusably rude to her vassal Brienne; and things were generally a mess at Winterfell, until they weren’t. Did Sansa know all along that Littlefinger was trying to manipulate her into fighting with her sister, or was she, for a time, duped by the late Petyr Baelish?

The script reveals it is the latter. Sansa gets ticked off watching her sister and Brienne spar in the courtyard, and worries Brienne might be an ally for her sister should Arya turn on Sansa. “Sansa is not happy about it” the script reads. Furthermore: “This disturbs Sansa; the woman she thought was her dedicated protector is actually a time share.” That’s why Sansa abruptly, and unkindly, sends Brienne away.

The tensions between Arya and Sansa are also very real (until they’re not). When Arya accuses Sansa of trying to placate the Northern lords to ensure they are on her side, the script explains: “Arya is right. She knows it. We know it. Sansa knows it.” Later, Sansa gets genuinely enraged by her sister’s constant accusations: “Now she grows angry, and when Sansa gets angry a steeliness enters her tone.” None of these fights are for Baelish’s benefit.

So when, exactly, did Sansa catch on? She may have had some private suspicions all along, but Baelish doesn’t make his big mistake until the season finale, when he tells Sansa that Arya wants to be the lady of Winterfell. Sansa knows very well her sister never wanted any such thing. The script outlines Sansa’s moment of dawning realization: “Littlefinger spreads his hands. Well? There it is. Sansa nods. There it is.” And that little moment marked the beginning of the end of Littlefinger’s climb.