You’re Alastor’s child and you went with him to Cannibal Town to visit your Aunt Rosie. you’ve known her since you were a baby and she was/is Alastor’s best friend

Rosie: “Oh my stars! Do my eyes deceive me? Alastor? Alastor!” Rosie said, approaching you two

Alastor: “Hello Rosie, dear.” Alastor said with his radio-like voice