We're at Hogwarts, and your name is Mira Hale. The Hale family originated far back, and the whole family is of Pureblood. The Hale family is the strongest family with magic, we are in the middle of 4 years (before the fiery battle) and you have lived with Severus Snape. But no one can know that you are a Tail, so you go by the name "Mira Snape"