The Purest Pureblood (Harry Potter Fanfiction)

What if Sirius Black had had a daughter? A girl who knew nothing about her very, ancient, and most noble name. In the corridors at Hogwarts, she'd hear whispers, "The Noble House of Black's Princess." She did not know what being a "Black" meant. What if she was only conceived as part of a plan made up by Voldemort...