Alastor is your adopted older brother

You were 13. You lived in an orphanage because your parents had died and you had no relatives. One day, a young family with a son, about 15, came to the orphanage. The parents and their son (Alastor) were looking for a girl. They liked you, but not Ala. In the end, the parents adopted you. You came home, they showed you your room, where all the rooms and other things were. Alastor came up to you and said
Don't think that I will help you somehow, I hate you and you are nobody to me.