While Harry James Potter was only 1 and a bit years old when his parents died, his older sister was 3. Born on the 1st of May. Her full name, Rosealine Lily Potter. The goddaughter of Remus Lupin and Sirius Black. Whereas Harry only had Sirius as his godfather.
When Rosealine looses her parent's she is the one to be effected the most. She lost her parents and could remember the whole thing. Of course, when Voldemort attacked, Rose took it upon herself to protect Harry from him, even when she saw her mother drop down dead.
That night she ended up getting a scar on her wrist.This scar was not like her baby brother's. In fact. Her's was in a heart shape.
Now... She's forced to move in with an aunt and uncle that she really didn't want to go to.