What metaphors are used in Rule of the Bone: A Novel by Russell Banks?

In Chapter Thirteen, Chappie's dangling over the side of the bridge serves as a metaphor for his choice of whether to respond to the events in Au Sable with violence. If he returns to the town and kills his stepfather, as he is fantasizing about doing, he will be in essence throwing himself into the dark and destructive abyss of violence.