...
This is the same girl who over the past few season has learned to "play the game" from Littlefinger and got so good at it that she outplayed him last season. Not only did she outplay him, but she was able to fool Littlefinger to his face by faking emotions. All of this happening towards a person who sold her to a sadist and betrayed her whole family for years. A betrayal that resulted in the deaths of her Brother, Father, and Mother. Yet she still played her role perfectly and never gave anything away. Thats not even mentioning all the times we watched her keep her emotions in check while being a prisoner at the Red Keep. Being polite even to those she utterly loathed and had every right to hate.
...
To be fair, she didn't so much outplay Littlefinger as him basically being an outward scheming asshole in front of her for the past 4 seasons or so.
She literally knew among other things that
- he was involved to some degree in the framing of her father (and did not help him get out)
- he was involved in forcing her hand to write a letter to Rob, creating a compromising document against her
- he organized Joffrey's poisoning, and framed Tyrion -and- her for it
- he, although saying he loved her mother, tried to molest her repeatedly and switched his story to "now it's you I love"
- he assassinated her Aunt in the Eyrie right in front of her, and then usurped power in the Vale
- he got her to lie to the lords of the Vale to save his skin
- he sold her to the Boltons to gain leverage in the North
- he repeatedly and fairly obviously tried to turn her against Jon, and then Arya
- I wouldn't even be surprised if it has been his idea to tell Sansa to keep quiet about the Vale knight reinforcements, let Jon go in the front line with Wildlings and see what happens
Still, Bran was needed at the end for her to piece it all together, revealing LF's involvment in the death of Jon Aryn, Stark/ Lannister hostilities, Bran assassination attempt and framing, Betrayal of Ned...
Smartest person in the 7 kingdoms ? Right!