Anger in The Underneath is represented mostly by the Ranger's inherently evil owner, Gar Face. Ranger, of course, is a mistreated dog from the bayou on the Texas and Louisiana border, chained under the house (hence the title The Underneath).
Gar Face has severely mistreated Ranger due to his anger. Ranger is shot by Gar face, and although it was accidental, that doesn't matter. Gar Face has exiled Ranger under the house. The irony is that through Gar Face's anger, Ranger is eventually freed. Gar Face continues to keep Ranger in "the underneath," but Ranger meets a cat who has kittens that Ranger names "Sabine" and "Puck." There is a real parental-type love between Ranger and the sweet kittens. It is this love that serves as the foil to Gar Face's anger:
Purring is not so different from praying. To a tree, a cat's purr is one of the purest of all prayers, for in it lies a whole mixture of gratitude and longing, the twin ingredients of every prayer.
There is also anger shown by the character of Grandmother, an old water moccasin snake (a cottonmouth) who has been trapped in a jar "for a thousand years." She is let out of the jar by a big storm. There is no angrier creature than a snake trapped in a jar! The snake, named "Grandmother" for her age, sees the love between the dog and the kittens and frees Ranger!
The anger of Gar Face is so severe that he drowns the mother of Sabine and Puck. As a result of his evil nature, Gar Face ends up dead. Death by anger is probably the most significant role of anger in The Underneath.