Who is Cress from The Fifth Sacred Thing and what is their importance?

Cress is a representative at the City's Council from the Water Council, Cress is combative. He strongly dislikes Bird. When the Steward armies invade, Cress is an outspoken proponent for a violent response. As part of the resistance to the Stewards, the Water Council, under Cress's direction, engage in unsanctioned direct action, exploding the dams the army has placed in the river.