After his father's untimely demise as a result of using a Delusion, along with Inspector Eroch ordering Diluc to cover up the incident, his faith in the Knights shattered and he left the organization. Even after Eroch was purged from the Knights for being a traitor, he still holds resentment towards them. After his father's death, he has been suppressing himself. Despite coming off as bitter and grumpy through his speech, he has a gentle, tender, and modest nature. Diluc is not fond of alcohol.