Who is Harvey from The Dead and the Gone and what is their importance?

Harvey owns a tailor and alteration shop before the catastrophe. In the wake of the disaster, he sees a way to make money, and he begins running a black market type of exchange service... people bring in goods and items, and Harvey exchanges them for food and other supplies. Harvey is not described as a bad person, but rather, an opportunist. Where the government fails, Harvey succeeds, allowing families like the Morales' to stay alive, and allowing people like Kevin's mother to hide their addictions.