One of the main themes is friendship. Jess and Leslie's relationship shows how a deep friendship can be a source of support and adventure. Another theme is imagination. The creation of Terabithia represents the power of their imagination, which helps them escape from the real - world problems they face. Also, there is a theme of growing up and dealing with loss. As the story progresses, the characters experience different levels of loss and have to grow and adapt in response.
The two main characters are Jess Aarons and Leslie Burke. Jess is a boy who is initially somewhat lonely and struggling with his place in his family and at school. Leslie is a new girl in town who is very imaginative and different from the other kids. Together, they create the magical world of Terabithia.