What is the theme in Slake's Limbo by Felice Holman?

One of the major themes of Slake's Limbo is hostility. Slake feels that he lives in a hostile world. No one has good intentions for him. Everyone is out to get him. Slake has no family, except for one aunt. The only thing the reader knows about the aunt is that she abuses Slake emotionally and physically. The boys at Slake's school are also abusive. They torment and harass Slake. They also physically beat him. For example, when he wears a new sweater to school, they take it off him and throw it around. When he gets it back, the boys chase him on the streets. Slake's life is dictated by the hostility of the human race. Joseph, the only friend he has, is a calming presence, but Joseph dies. Slake now must escape the hostility of the above ground world and go into the subway.