She was an orphan. She hadn't been in a real family since her Muggle parents abandoned her crying on the dirty streets of london. They didn't want a witch for a daughter. Coincidentally, those dirty streets were also the doorstep of a certain dark wizard. She was named Kia, and raised by Severus since she was 2. Severus was not proud of having a mudblood daughter. Therefore, he tried his hardest to make her seem as powerful and talented as he. She was also raised in the halls of hogwarts. Because of severus, she would watch all of his Potions lessons. She would also constantly visit whichever DADA teacher was teaching that year.
Now, she is an established witch, and a master of Defense against the Dark Arts and Potions with the help of her father.