Who is Charlie from Earth Abides and what is their importance?

Charlie is in the company of Richard and Robert who travel out from Ish's tribe in order to report on the condition of the world outside their own community. Charlie charms several of the older people and some of the younger and apparently has sex with Evie, a young, simple-minded woman. Charlie tells Ezra that he has sexually-transmitted diseases, and it's known that he carries a gun. Charlie is hanged by a unanimous vote of the makeshift council of rulers as they fear what he will do to their community and their young people.