Finding yourself
Austin Szerba and Robbie Brees have each other, but that is essentially all they have. They are bullied in school and grows up not knowing who they are or what their place in the world is. They are finding out what they want to do and where they want to go, though the world takes a sharp turn for the worse. Austin and Robbie don’t only have to save the world, but they must stand against bullies and degrading comments at school and in their free time. Therefore, as many other young adult books out there, Grasshopper Jungle has both an adventurous plot with a "coming of age" theme fit for its readers.
Sexual orientation
It is clear in the beginning of the book that Austin Szerba is heterosexual male, because of his girlfriend Shannon Collins. They seem to be very serious, but slowly and surely the reader understands that Austin has conflicted feelings. He has sexual fantasies and thoughts about both his best friend Robbie and his girlfriend Shann. He never acts on these thoughts, which means that he never gets to know about the fantasies Robbie also has for Austin, because they never open up to each other.
Apocalypse
Apocalypse and the fight against it are obvious themes in the book, as the plot is heavily based on it. Some bullies trigger the plague through Robbie’s blood, and it is quickly taking over the world and spreading. The world is ending, and the only way it won’t perish is through the hard work of three friends. Sadly, they don’t manage to save the world, and they have to live on their own in a shelter.
