One of the best characters in the first Fantastic Beasts film, Modesty Barebone, was left alone in her old childhood home, abandoned both by all adults and her brother Credence (who turned into Obscurial, so he was really not in a shape to take care for her), and never mentioned again (AFAIK).
Let me start here small story as a prompt:
She didn’t even know why she took pieces of the wand with her when she left for her old childhood home. When Credence exploded and left she was completely washed in pure magic. She thought in the first moment, that she is going to die, that the explosion is going to kill her. But nothing like that happened. Credence’s magic recognized her and protected her even when the whole building collapsed around her. Showered with magic, she saw weird fragments of stories in front of her eyes, she heard sounds she couldn’t hear, she was flying in the middle of the room for a moment, she lost consciousness in the end.
When she woke up, she was in the ruins of the building, hidden in the hole in the wall just the size for her to comfortably fit in. After the experience of the pure magic surrounding her, she was not even surprised when she found out that pieces of the wand Mary Lou broke were together again and the wand was pleasantly warm in her hand.
So, that is how it was: abandoned and lost little witch with her wand in the middle of New York with nobody knowing about her, without any food and without any money …
That’s it. I would like somebody to continue with this story. Little (eight years old) girl living on streets of New York, who has wand (well hidden, because she knew from the experience with the New Salem Philanthropic Society that many people could hurt her), but not much else. She will have to learn how to live on streets with the children gangs of New York, and perhaps later she will meet somebody who will teach her to use her magic. Something like a cross-over between HP universe and Oliver Twist.
Inspired by the linked prompt, but I have never seen anybody to pick it up and do it justice.