The White-Haired Black (a Harry Potter 19 yrs later fanfic)

Avery Collins just turned eleven years old. Her Hogwarts letter arrived at her Muggle family's London townhouse, accompanied by the Headmaster of Hogwarts. He takes her to stay at the Potters in her last week of summer, where she begins to notice that there is something weird about her real family-not the Muggle family that took her in. It isn't until she arrives at Hogwarts that the truth is finally revealed...but who really is Avery Collins-and what happened her entire secret magical bloodline?