Marinette and Felix had always been rivals in school, always fighting, disagreeing and provoking one another. Until one day, Felix corners ladybug as she de -transforms, eyes closed. Why was he here? He wants ladybugs help to solve a mystery of his. Everyone believes that his father and Adrien's mother both died last year, however he isn't so sure about that. What is his theory? Adrien and him are not cousins, but half brothers, and that their father has run away with the Emilie "agreste." But the story doesn't stop there, it only starts to unfold when the famous model and fencer Adrien Agreste hires Marinette as his tutor, and possibly his part time girlfriend after quitting his lifelong dream of fencing.