you are actually the daughter of Severus Snape and Lily Potter, therefore Harry’s half sister. You grew up with your father, and the Malfoy family, since they’ve always been friends. Your father often told you how James Potter bullied him in his school time, so you practically knew everything about that.

you‘re in 5th year at Hogwarts, in Gryffindor. Yesterday night you went to sleep like every other day.

but you just woke up, and when you went into the common room, you didn’t knew a soul. But there was a group of five, that you knew from your father’s yearbook. The marauders. James Potter, Lily Evans, Remus Lupin, Sirius Black, and Peter Pettigrew.

during the day you realised that you’re really in the 1970s, travelled back in time like it seems. As you walk down a corridor, you see the marauders bullying a Slytherin student. When you step closer you realise that it’s your father. But of course Severus couldn’t know you, since this is the teen version of him.