Margarette Dupain-Cheng is Marinette's younger sister by some months. She has the "Butterfly Miraculous" when inhabited by her kwami, Aya she transforms to the well-known "Papillon Bleu" The girls knows about each others identity and are partners in solving crime. Margarette also knows about Marinette's huge crush on the world famous model, Adrien Agreste who goes to the same school as them. Margarette too, has a crush. And that's no other than "Chat Noir." But she knows about his feelings for Ladybug, her sister. She feels sad but nonetheless supports him. What she doesn't know, that the things in her life that was slowly falling apart, was actually falling into place.