A red-haired young man who serves as the owner of Dawn Winery, Mondstadt's largest winery. He once held a high-ranking position in the Knights of Favonius.

Since becoming owner at a young age, he has demonstrated the judgment and intellect to revitalize the winery in a short period. He possesses a wide range of accomplishments, from handling all types of weapons including swords and bows to performing difficult musical instruments, and is well-versed in cooking and chess.

He possesses a strong sense of responsibility and duty that leads him to distrust public servants for personal reasons. While keeping his distance from the Knights, he works behind the scenes using his wealth and information network to the fullest, and at night, he fights alone against the monsters that threaten the people to protect Mondstadt.

His secret activities have earned him the nickname "Darknight Hero" among the residents of Mondstadt, but he himself has no good feelings toward this name, finding it "unbearable" and cringing at the naming sense.

As a result, he leads an extremely busy life as both a winery owner and a shadow hero, and at night, he sometimes stands as a bartender at his own tavern, Angel's Share. One wonders when he sleeps.

Diluc was once surrounded by bouquets and applause, with great expectations from those around him.

He manifested a Vision at age 10, joined the Knights of Favonius at his father Crepus's wish, and eventually became the youngest Cavalry Captain at age 14.

He was a serious child who carried his father's expectations from an early age and disciplined himself strictly; it is said he would freeze in confusion if his father told him he was free to do as he pleased.

What made him happier than anything else was "being praised by his father," and he adored his father almost blindly.

However, to save his father from the suffering caused by the backlash of a Delusion, Diluc had to end his most beloved father's life with his own hands. Since then, he has lived suppressing his various emotions.

Following this incident, he resigned from the Knights of Favonius, discarded his Vision, and wandered the seven nations to uncover the truth behind his father's death.

Even now, his father remains a lingering pain. Diluc has become a hero who inherited his father's will.

He is willing to sacrifice himself for a greater cause, but he is not a man indifferent to the pain he feels in the process. Diluc rationally understands the necessity of facing challenges and moving forward for the sake of others.

On the other hand, he is tormented by a sense of responsibility that pulls him away from his gentle past, and he struggles to discard those emotions, possessing both mental strength and fragility.