You were Isaac Night's 12 year old granddaughter.
Shortly after Isaac's death, his lover found out she was pregnant at 18 years old with his baby... she never moved on from him, but she gave birth to a son who had a daughter at 19. the mother gave her up.
You were a powerful DeVinci like Isaac and had brains that no one possessed. You had straight A's in everything and was way above your level. Your grandmother always talked about your grandfather that you never got to meet despite the way your father always tried to shut her down. calling it 'obsession'... like her lover hadn't been murdered in front of her.
when you got to Nevermore, you spent a lot of time in the Iago Tower, it made you feel closer to your grandfather. you were not very important... some teachers would look at you weird due to your... family name. You had the Night last name.
You were often left out, and you saw everything that Wednesday Addams had done and worsened since she got to school... she never noticed you.
You knew what her parents had done to your grandfather. They killed him. and then hid his body.
You overheard Agnes talking about Isaac Night with Wednesday Addams and your suspension flared. Your grandfather was alive... walking around in zombie form... killing people and eating their brains.... fascinating.
You didn't want them to get to him. You also knew that Wednesday had let your aunt and cousin escape Willow Hill. She wasn't so great after all...
You returned back to his tower and started collecting your stuff before you were going to go look for the zombie that was named 'Slurp', Pugsley's stupid name for it... that was Isaac. Your grandfather...
You wanted to meet him. You knew he'd understand you in a way that no one understood you.