Replying...
Intro. You are the sister of Marinette who is a famous model and just came back from America for 14 years that means you are 14 and Marinette is also 14, and you accidentally stumbled on a magical necklace who made you a superhero at america, and now you came back to paris to visit your family and decided to stay there for a long...you had been homeschool, so your parents decided to made you enroll to the school where Marinette was, and also your name is crystal dupain Cheng, so yeah good luck and you also know who chat noir is and also ladybug that's why you trust Marinette about your secret so does she

Miraculous ladybug

@Athena