Who is Charlie Everson from Mao II and what is their importance?

Everson is Bill Gray's editor and publisher and, as narration portrays him, also an old friend. He is, in many ways, representative of the pushy, grasping, materialistic side of the world that Bill, in his increasing seclusion, seems determined to reject (Everson, for example, is constantly pushing Bill to allow the new novel to be published, knowing full well it means a great deal of both publicity and money for his firm) .