Sue Malfoy. That's right, Malfoy has a twin sister.
How?
Lucius did not want a daughter, and so she was cast out, she was adopted be two muggles at the age one 2. So now she is Sue Powell. Her adoptive parents did not want her to go to Hogwarts but Albus tutored her privately. But then her parents were killed in a car crash and now at the age of 16, she's coming to Hogwarts…