What is the theme in Eragon: Inheritance Book One by Christopher Paolini?

One important theme in the novel is that of friendship. Murtagh and Eragon, Brom and Eragon, and Saphira and Eragon all share the bonds of friendship. The most important bond is between Eragon and Saphira. There is love and affection between them, and they are very protective of each other. Brom's relationship with Eragon begins as one of pupil to teacher, but their relationship evolves into friendship even though they were not peers.

Since they are the same age and of the same fighting ability, Murtagh and Eragon are definitely peers,. They quarrel like boys, fighting with each other when they have become tired and irritable, but they care for each other. When Murtagh is incarcerated at Tronjheim, Eragon frets about his friend, whom he is relieved to find out, has been treated very well by the Varden.