one part of the trident scene that I find so compelling is sansa’s reaction to joffrey holding a sword to arya vs arya holding a sword to joffrey. obviously I love sansa so this is not to disparage her as a heartless sister or anything like that (not that she’s a good sister to arya but that’s a pretty reductive way of understanding sansa’s psychology in this scene), but more that it’s such a great way of introducing sansa’s tendency to repress or rewrite memories in order to make trauma easier to cope with.
to start with, here is her reaction when joffrey holds a sword to arya:
Sansa was shrieking, "No, no, stop it, stop it, both of you, you're spoiling it," but no one was listening. Arya scooped up a rock and hurled it at Joffrey's head. She hit his horse instead, and the blood bay reared and went galloping off after Mycah. "Stop it, don't, stop it!" Sansa screamed. Joffrey slashed at Arya with his sword, screaming obscenities, terrible words, filthy words. Arya darted back, frightened now, but Joffrey followed, hounding her toward the woods, backing her up against a tree. Sansa didn't know what to do. She watched helplessly, almost blind from her tears.
here sansa is specifically described as being BLIND from her tears. she cannot make sense of joffrey’s behavior because it doesn’t fit into any narrative that she’s ever been taught about princes, knights, people in power who are supposed to defend the innocent. she initially screams at both of them to stop, but when joffrey gains the upper hand, sansa freezes and is so overwhelmed by confusion/shock that she becomes “blind” with emotion. she doesn’t (or doesn’t want to) fully see what’s right in front of her, which paralyzes her into inaction while her little sister is being threatened (think of her coping mechanism when joffrey forces her to stare at ned’s head, “He can make me look at the heads, she told herself, but he can't make me see them”).
compare this to when arya holds the sword to joffrey:
The direwolf let go of Joffrey and moved to Arya's side. The prince lay in the grass, whimpering, cradling his mangled arm. His shirt was soaked in blood. Arya said, "She didn't hurt you . . . much." She picked up Lion's Tooth where it had fallen, and stood over him, holding the sword with both hands.
Joffrey made a scared whimpery sound as he looked up at her. "No," he said, "don't hurt me. I'll tell my mother."
"You leave him alone!" Sansa screamed at her sister.
now she’s screaming at arya for doing the same thing back to joffrey, not because she hates her sister or doesn’t care if she’s hurt, but because arya acting out makes sense to her. it’s been drilled into her for her entire life that arya is the “bad” sister because she refuses to conform to highborn womanhood, she mingles with common born people, she doesn’t have respect for authority, etc. and now sansa is literally watching arya use a sword against the crown prince, all of which fits the narrative that she’s been fed by the adults around her. she finally finds her voice and screams at arya because she can, it’s something that she feels is within her power/understanding to do something about (also because it’s easier for her to stand up to her little sister than it is to stand up to a prince).
and ofc sansa latches onto this image (arya holding a sword to joffrey) to later rewrite the entire memory in her head until she fully remembers a different version of events and doesn’t understand why arya is accusing her of lying. in fact she already starts doing this right after arya and nymeria run off (although not completely since she goes back and tells ned the truth of what happened, and only fully rewrites this memory when she’s unwilling to blame joffrey for lady’s death):
After they had gone, Sansa went to Prince Joffrey. His eyes were closed in pain, his breath ragged. Sansa knelt beside him. "Joffrey," she sobbed. "Oh, look what they did, look what they did. My poor prince. Don't be afraid. I'll ride to the holdfast and bring help for you." Tenderly she reached out and brushed back his soft blond hair.
none of this is to say that sansa dealt with this event in a healthy or commendable way, but I do think that it gives us a really interesting look into how this sheltered and terrified 11 year old makes sense of an incredibly traumatizing event, especially when she’s inclined to cling onto the familiar/comfortable already. super fascinating!