Who is The Fat Man from The House of God and what is their importance?

The Fat Man is a second year resident and works over Roy on the medicine ward. The Fat Man is a heavy man and legendary, according to Roy. Described as "Brooklyn-born, New York City-trained, expansive, impervious, brilliant, efficient" and having sleek black hair, sharp black eyes and a bulging chin. He has some of his own ideas on the taking care of medical patients and has invented several irreverent rules that he shares with the new interns. The Fat Man's goal is not to touch another patient and to let the interns do it. The interns love him but think he's crazy.