compare and contrast the two parents and their relationships with their children.

This is very much a theme in the story. The boundaries that are recognized between parents and children simply do not exist in the Walls household. Rex describes this concept of physics after Brian and Jeannette almost die in a fire they set while playing with toxic waste. He warns them that no rules exist in the Boundary between turbulence and order and that if they do, nobody yet understands them. That day he says they have gotten too close to the boundary. In a way, the Walls children live in perpetual proximity to this boundary. After Rex begins drinking heavily and there is no food in the house, they begin scavenging for food and clothing through various means and enter into a place where rules and order no longer exist. The Boundary reappears at the end of the novel when Jeannette remarks that the flame of the candle is bordering the boundary between turbulence and order. This suggests a relation between this boundary and the ever-present fires of the novel; both represent chaos and control throughout the work.