Who is Charles Hayman from Richard Brautigan's Trout Fishing in America ; the Pill Versus the Springhill Mine Disaster ; and, in Watermelon Sugar and what is their importance?

Charles Hayman appears in the story, Trout Fishing in America. He builds a shack in 1976, where he can stay while fishing for trout in a nearby creek. Hayman lives on a diet of stone-ground wheat and kale, and he is described as someone with no appreciation for children.