PT 1: hey dunno if u ever talked about this before but ive been thinking about like. say seer powers - do we have any reason to believe either way that such powers would be designed to show the player all paths/options possible for them, or could it show manipulate them into doing something that has to be done according to timelines? example: terezi only saw the options to kill vriska or spare her then get killed herself....

… PT 2: BUT later in retrospect terezi saw the option to knock her out and got john to do so. do you think this proves that her powers don’t in fact show her all options but are very much limited by the game to manipulate her into making the Game Over timeline so that there would be a john and a roxy for the alpha timeline? so maybe her powers purposefully only showed her options that would get her doomed? hhh i hope this makes sense

Aranea addresses this very thing about Terezi, what agency would a person who at any moment perform literally any action and lead down an infinite different paths? How is a Perfectly Generic Being any different from someone slated for predetermination and fate? Terezi doesn’t see all the Choices, she sees all the Choices she would be capable of performing. The binary choice at that moment is not for the Alpha Timeline or what Fate has in store for her- It’s what she, in the heat of the moment, facing Vriska, could do. Let her go, or kill her. That is simply the only thing she could come up with, the only thing she could. Get left behind and perish, or kill Vriska and deal with the consequences later.

That being said, of COURSE Terezi didn’t see the third option of knocking her out- She literally couldn’t have, that choice only came about after she sent John, now unstuck from the Plot itself, back in time.

Think about it like Garnet from Steven Universe. She can see literally every branching path, every, in her Mind’s Eye, but to narrow it down to the ones she know are plausible, she has to assume what others are going to do. That is what Terezi sees, not every single possibility ever, but, what according to her knowledge, and the power she herself holds over what’s going to be happening, could happen. And that’s also why she leads John down different points of her own story- Moments she herself recognizes, pivotal moments she did something or chose something that she can find in the vortices of her memory to show him the way. 

Before she knew about John’s Retcon, before John’s Retcon ability was introduced, there was NO way for her to factor said choice into the equation. And she couldn’t have like… Talked her down from it. That’s just not the kind of person Vriska is. She knows it. She could’ve also not stalled until the others arrived. Or maybe she could, but she felt she couldn’t. That’s what that Choice meant to her. It was Do or Die time. And she chose Do. Her hand was forced, by her own foresight of what was going to happen if she let her go, to take action, and as such, she never felt like she made the right choice- Like there WAS a right choice. And it haunted her until the moment she dropped dead.