The definition of Forever King
As I know "Forever King" is the title for Driscoll. I never heard Urien or Patrick had being called as it. Ben had said "Urien, Patrick, The Forever King?" in the episode "The Creature From Beyond" in UA when he was talking to Cyrus. I think Urien and Patrick can only be called "Faction Leader" and "Forever King" is only for Driscoll.