Bullying
The principal theme of the novel is bullying. The author was bullied at school himself because he had a speech impediment and because he felt isolated by this he dropped out of school and his life took a very negative direction. The novel deals with the fact that teens who are being bullied feel as if they are the only ones who are being bullied; they don't know where to turn, and nobody is looking for the signals that they are being bullied. Myers intends the book to show that bullied teens are not alone and are in fact many in number, hoping to inspire them to seek help. The theme extends to showing how bullying escalates and Pushes a person over their limit so that they act in ways that are out of character as a result of the bullying. Leonard is an extreme example of this as he becomes a school shooter; however since three of the main characters are all being bullied, the theme of the effects of bullying is seen through the experiences of three different teens.
Poor Parenting
One of the things that Cam and Leonard have in common is that they come from dysfunctional families. The absence of a strong parental figure is a sub-theme of the novel and its effects are wide ranging. Having no parental guidance or support also makes the teens feel even more isolated as they don't have anyone fighting their corner. Poor parenting also means that rather than spotting the signs of Leonard's downward spiral (drug abuse, gun obsession) these things went unnoticed at home and the feeling of isolation and loneliness is intensified.
Drugs
Leonard is abusing drugs, and this is one of the themes of the book that adds to the undercurrent of disaster in his life. The themes are also presented as a whole to show that bullying triggers a chain of events that all lead to a life unraveling. Leonard seems to have problems with impulse control as his reactions are far more extensive and extreme than Cameron's but part of what adds to his isolation is the effect of his drug abuse.
Ignoring Warning Signs
Cameron tells investigators that he is not surprised that Leonard was the shooter because there were lots of things that pointed to his life being out of control. He was abusing drugs. He was compiling a list of enemies. He was obsessed with guns. All of these warning signals were things that occurred retrospectively to Cameron as factors that foreshadowed Leonard's killing spree; however, the adults in his life, including teachers and parents, should have been able to see a couple of these signs and step in before matters escalated. The theme of missed warning signs includes missing the signs that the kids in their cafe were being bullied and suffering as a result.
