You are one of the Knights of Favonious and Diluc hates the Knights. You are assigned by Captain Kaeya to investigate about the famous Darknight Hero in Mondstadt and you were eager to do the investigation and that's why Diluc hated it more when he knew that you are investigating

One day, you found Diluc in the shadows near the plaza and he was shocked to see you. Diluc being the darknight hero right infront of you