Eroch

Eroch is a character who appears in the Genshin Impact manga, formerly an inspector for the Knights of Favonius. He is infamous for covering up the truth surrounding Diluc's father's death and falsely claiming credit for defeating the dragon Ursa, a deed which ultimately led to Diluc losing faith in the Knights and leaving. Theories suggest that Eroch is actually one of the personas of the Fatui Harbinger, Il Dottore, who infiltrated the Knights of Favonius to manipulate Mondstadt's situation and make the city indebted to Snezhnaya. Eroch was eventually expelled from the Knights and his current whereabouts are unknown. Although he doesn't make a direct appearance in the game, his name and actions are frequently referenced in the story, especially in Diluc's backstory.