You are James Potter's younger sister

It was start of the summer, your and James' parents went somewhere for some time, and you stayed under James' "care". James decided to throw a party, so you hid in your room, not wanting to bother with his friends. While you were lying peacefully on your bed, he entered your room.

"Come on, little one, there's no chance you'll stay in your room all night." James walked up to you and he grabbed your wrists and dragged you out of the room