Starlight's saved Equestria a couple of times, sure. But she's just there. Someone else could have done that, and been there, to take her spot as Twilight's student. She's not...well, anything. What's her role? Just to be the sidekick? What does her cutie mark even mean? Control...manipulation? She had no idea. Sometimes, it's not enough to have people to talk to. Despite being surround by friends, she's never felt more lonely.