Now I know this isn't accurate to the books, but I hope you like it.
The Beginning of The Marauders
The Story of Remus Lupin
I look outside my bedroom window at the rain hitting the pavement. My mother and father were fighting again. My father was shouting about how Fenir would be here any minute and that dinner should already be on the table. My father and I are wizards. I'll be going to Hogwarts School of Witchcraft and Wizardry in a month. Fenir Greyback was a friend of my father's and came over for dinner every other Friday. There was always something fishy about him but I couldn't figure out what. Anyway, my mother was a mudblood, or a muggle-born, and I think the only reason my father ever married her was so he didn't have to find a house elf. She's actually quite a brilliant witch.
Just then I saw the dark figure that was Fenir start walking up the drive. I ran downstairs to open the door (because that's what the duty of a child is, to be quite and polite). Fenir never approved of my father marrying my mother, and he had a nasty temper, at least once during the night he would use the Cruciatus Curse on her. My father would just sit and laugh. Well, now that I had my own wand, if he tried to hurt her he would be getting a taste of his own medicine…