Despite possessing some knowledge of who Lelouch is and of his power, Diethard remains loyal. Only when Lelouch is exposed in front of the leaders of the Black Knights does he betray him. He claims that he would rather have watched Zero topple Britannia, but will settle for a hero's death instead. When finding Lelouch proves difficult following his escape, Diethard suggests reporting him as dead, noting that even if Zero came back he would have no credibility without support. He defects to Schneizel following this. When Schneizel is placed under Lelouch's control, Schneizel fatally shoots him in the heart before he could shoot Lelouch.
