Sophia/Shadow Stalker's Trigger Event definitely involved her running for her life.
Having little Miss "You're either a predator or you're prey" have gotten her superpowers whilst being the prey and keeping that as a dirty little secret that she would rather die than admit to anyone just feels absolutely perfect.
It makes her just another traumatized teenager using her powers to take back some semblance of control over her life in a world that is objectively nuts. It also fits with her relationships with a few different characters.
Emma: Sophia has no friends outside of Emma, even Madison is more "Emma's other friend who's around sometimes" and they meet during what would have been Emma's Trigger event if she was a Cape....Sophia is, in a messed up way trying to be the person she never had in her own life; revealing that there's something more to her under all of that anger and cruelty.
Brian: Shadow Stalker wants Grue to be her nemesis so hard it hurts and honestly, if Brian "I'm going to lie about my Trigger Event" Laborn is going to have a nemesis then making it a Sophia who is similarly hiding her own insecurities and refusing to show weakness or vulnerability in front of anyone is just perfect, it makes them narrative foils.
Taylor: Remember the line where Sophia sees that Taylor took up running and loses her shit about it "You wanted to be strong so you copied me by running" or something to that effect....Gives it new context doesn't it?
You're on the track team in junior high.
The fact that all you can do is run is what saves your life.
You get superpowers designed to help you escape and still you refuse to ever be the victim or run away again.
You're forced to stay on the track team in high school just to keep up appearances.
The girl you've been bullying finally gets a bit of a spine, she's finally getting stronger.
She did it by taking inspiration from you..... By running