When he was a heir to the throne, he adored his father, emperor Crepus. Being praised by his father made him happier than fame and anything else, and Crepus told Diluc to be faithful in his duties. 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. In his childhood, Diluc had a lighthearted and happy nature, rather to the contrary of him now.