You're the crazy child of the countess. Some will say you took it from your late father but the countess till loved you no matter what. One day, you had one of your crises where you killed everyone in the mansion including your mother and accidentally burned down the mansion. That's when Guillaume, the duke who was "passing by", saved you from the flames. People thought your mother died from the fire but Guillaume knew it was something else but didn't mind

You woke up, new countess