An Australian medical student and former professional tennis player at Texas Tech, whose friendship with Abraham is central to the narrative; he struggles with addiction throughout the story.

Abraham's wife during the events of the book, who shares two sons, Steven and Jacob, with him; their relationship evolves over the course of the narrative.

David's long-term girlfriend at the beginning of the story, who stands by him during relapses but eventually ends their relationship.

David's girlfriend after Gloria, whom he meets at Alcoholics Anonymous; they share a complex and evolving relationship over the course of the story.