Fatgirl
Steph realized early that she was the only Bat to have earned an actual nickname from the bat brat, the only person in the world as far as she could tell that the runt called anything other than a proper name, a generic insult, or a more creative one-time insult.
Sure, "Fatgirl" was still an insult. But insults were the only way Damian ever showed affection and given his well-known aversion to nicknames, she felt pretty special.
She had worked for that title as much as any of the others she'd carried and she was just as proud of it.
Listen up, y'all. Stephanie Brown does not get nearly enough love and credit. She was both Robin and Batgirl, the only person in the world to hold both titles. And yes, I know she was Robin for like a week and was given the title basically so that she would fail and Tim would come back, but she rocked it. And listen, this is a girl who realized her dad was a criminal and decided to do something to stop it; she literally became a superhero fighting her own father, which is a hard thing to do. And she was like "I need to hide my face," but because she's so extra (literally destined to be a Bat, this one), she designed and created an entire superhero costume, super dramatic and in her favorite color (seriously, such a Bat). And when Batman told her to stop, she told him to mind his own business and punched him (stubborn, another Bat-trait). And later when she took over the mantle of Batgirl, she changed up the costume because she's her own person.
Also, the Batgirls handled transitioning and their relationships with the others a lot better than the Robins did. There are a lot of reasons for that; I'm not at all saying that it basically boils down to the removal of Bruce's direct influence on participants and process alike. (Totally not saying that. At all.)
Okay, yeah, basically, the Bats were never great at communication, but Bruce's direct influence made them worse and the fact that he repeatedly took Robin away as punishment and passed it from Dick to Jason without consulting Dick who created the persona as a tribute to his parents kinda started a cascading issue there. Unlike the Batgirls, who operate with Batman rather than directly under him and pass it on when they are ready. But that's a discussion for another time.