I always wondered why GRRM drew such a stark difference to the way Arya and Sansa have to behold their father’s death, with Arya blind to it and Sansa with eyes wide open.
Dimly, as if from far off, Arya heard her sister scream. Sansa had fallen to her knees, sobbing hysterically. Ser Ilyn Payne climbed the steps of the pulpit.
…Arya was wrenched off her feet. She would have fallen if he hadn’t held her up, as easy as if she were a doll. A face pressed close to hers, long black hair and tangled beard and rotten teeth. “Don’t look!” a thick voice snarled at her.
No one cares if Sansa sees what’s about to happen; if anything, they want her to, to teach her a lesson, to show her what happens to traitors. Yoren ensures Arya cannot see what they are doing to her father, even if he has to be violent with her. And I realized the reason for one being forced to watch and the other being forced blind is because Sansa needed to have her eyes opened while Arya didn’t.
Sansa was too busy falling in love with all the fanciful people of the capital, most notably the royal family. Even when she saw Joffrey’s true colors at the Trident, she let his “indiscretion” go because A) he was her future husband, and B) she didn’t exactly want to. She was so willfully oblivious to what these people were that when it came down to one of the most important moments of her life, the wool was violently pulled from her eyes to show her the truth, whereas Arya had always distrusted the Lannisters and kept a suspicious view of King’s Landing since the moment they arrived.
Even after Ned’s death, we finally get to see how Sansa dealt with the beheading as she agonizes on repeat over the way her father’s legs jerked when the sword came down. It’s a cruel, sick lesson, but it was one that was imperative for Sansa to learn; one, that I believe, helped her survive King’s Landing as a hostage alone.