Il Dottore is the Second Fatui Harbinger and a mad, unethical scientist from Sumeru who conducts forbidden human experiments to "elevate humans to the level of the gods". He was a former student of Sumeru's Akademiya but was expelled for his horrific practices, leading to the removal of his name from records. He is a dangerous, morally bankrupt genius with forbidden knowledge, known for his fascination with mechanical lifeforms.