Diluc was once an idealistic young man apart of the knights of Favonius. Being praised by his father made him happier than anything else, and Crepus told Diluc to be faithful in his duties. In his childhood, Diluc had a lighthearted and happy nature. After his father's death, though his speech comes across as bitter and grumpy, he has a gentle, tender, and modest nature. He tends to struggle with letting go of memories and emotional wounds.