Stephanie Brown for the headcanon game please!!
You, I'll have you know, were actually first (good job), but I've been sitting on this one because my canon knowledge for Steph is bad and my fanon knowledge for Steph is bad, so she's in the pile of characters I have yet to get a good grip on.
Of the melange of canon backstories I've seen for Steph, my personal (admittedly sketchy) interpretation for Steph thus far has been:
Lower-middle class kid (not poor-poor but definitely a "one emergency from disaster" type household)
Lived on the edge of the Narrows and went to a low-ranked public school, so she identifies more with Jason's end of the spectrum than Tim's
Her dad is the standard crook/deadbeat/conman. Not physically abusive to her, probably but neither caring nor present. Very self-centered, definitely verbally harsh at best.
I don't ascribe to the nurse-stealing-opioids version of Steph's mom. I think her mom is a nurse and works long, unappreciated hours. She loves her daughter, maybe a little abstractly, and tries to be what she thinks a good mom is, but she's essentially a single parent whose deadbeat ex shows up to cause problems from time to time. Once Cluemaster is off the game board and Steph is a little older, I do think they have a bit of a trauma-bond relationship thing going on.
Headcanon 2: May or not be realistic, is definitely funny (at least to me)
Stephanie absolutely tries to rename herself at multiple points in her childhood. If you keep her rooted in the time she was created, she's one of like seven Stephanies in her class. If you affix her more towards present day, Stephanie is a dated name and she doesn't like it.
She absolutely goes the Anne Shirley route and picks a name she feels has pizazz and tries to get her classmates and teachers to roll with it. Alas, they do not. It does not help that she tries this at least three different times.
Headcanon 3: Evil and heart-breaking why would you do this
Not evil or heart-breaking, just softly melancholy.
Stephanie does. not. want Bruce to be her dad. No thank you! She's done with dads as a concept anyways, but if she were in the market for one, it wouldn't be Bruce Wayne, are you crazy? (If she had to pick, maybe if forced she would pick Jim Gordon, because she sees how he treats Barbara and she hears how Barbara speaks about him in return.)
Bruce Wayne, though? No way, Jose.
But she cannot escape the fact that every kind thing he's ever done for her, every quiet word of praise, every awkwardly tentative pat on the shoulder, every time he's stopped and just rested a heavy hand atop her head, as if taking a moment to soak in her presence was all he needed, has been indelibly carved into her brain for all time.
She doesn't want a dad, and she doesn't want Bruce to be her dad, but secretly she's glad she does have a Bruce.
Headcanon 4: Doesn’t align with canon (or maybe even reality) but I do what I want
By the time Stephanie is in her mid-twenties, her hair has darkened so much, it's more accurately classified as an undistinguished light brown. There, I said it. Stephanie Brown bleaches her hair as an adult.