Mathis lives in Forster Hollow, West Virginia and refuses to leave his home, even after Walter and the Cerulean Mountain Trust have bribed the rest of his neighbors to get out of town. His family has lived there for generations, and he resents Walter coming in from the big city to tell him he has to move. Well, OK, he really hates Walter too – and for good reason, since Walter calls him "stupid" to his face (3.3.31). Eventually they…well, to be honest, they "make him an offer he can't refuse," to quote an over-quoted line.
Karl Marx would tell you Mathis represents the proletariat: the powerless lower class manipulated by the wealthy and powerful.