In our reality Dr. Fate is a malevolent mystical hero. In the Justice Lords world he has been corrupted by a very powerful evil demon. He was responsible indirectly for Luthor's plot witch lead to his death and the forming of the Justice Lords. He is the one who planted the idea in Luthor's head about running for president, and in Astral form pushed Superman to do what he did to end Luthor's life. Secretly he is the cause for the deviation from the normal timeline. So it goes to figure he would join the lords with his own secret agenda. To bring his demon to our world where he will rule supreme. He has yet to find a way to bring it over but not for lack of trying. Several former heroes have been sacrificed on his alter. Though he dare not try using a Justice Lord or his plans might be discovered. Right now he's just waiting for an opportunity to find a hero as powerful as Superman or for Superman to falter so that he can use him to summon his master.