Grief
Grief is one of the most significant themes in Dani Shapiro's Signal Fire. In Shapiro's novel, even though it seems that Dr. Wilf has no relation to the teen that was killed, he deals with tremendous grief over the teen's loss. His life is ultimately turned upside down by the teen's death. He is wracked with grief and guilt. His life, at the end of the day, is transformed for the worse because of his misplaced grief. Grief, in other words, is one of the most profound and transformative things a person must deal with.
Kindness
Kindness is one of the most important themes in Signal Fires. Despite living much of his life in misery over the death of the teen and his wife's decline and ill health, Dr. Wilf is fundamentally changed by the kindness of young Waldo. Waldo, who is able to sense other people's emotions and make them feel better, makes Dr. Wilf feel like a new person. Waldo makes him feel appreciative, content with his life, and much happier. Kindness is one of the most transformative tools that can affect a person's life.
Making a mistake
Perhaps the most tragic, but significant, theme in Signal Fires is making a mistake. Many characters in the novel make mistakes. However, perhaps the most significant mistake is that of the teenager who goes out drinking despite being underage. Then, the teenager got into a car and drove home, crashing and killing themselves along the way. That single decision, to drive while drunk, affects the lives of countless people in the neighborhood, most especially Doctor Wilf. There are mistakes that someone can come back from, as Dr. Wilf shows, but there are also mistakes that people cannot come back from, as shown by the teen who dies.
