Sal Paradise is a well-educated young writer who seeks to understand his existence while traveling cross-country with his friend, Dean. Unlike Dean, Sal had a semistable upbringing and, as an adult, lives with his supportive aunt. He joined the merchant marines and uses money from his GI checks, as well as publications, to fund his cross-country travels. While he enjoys the debauchery of life on the road, Sal is also searching for meaning: connections with new friends, exploration of culture, and ultimately, answers about his place in the world. At the end of the novel, Sal matures and finds a quiet life to settle into. When faced with Dean at the end of the novel, he finds their lifestyles are no longer compatible: he has changed and grown but Dean never will.
Dean Moriarty is, in many ways, the novel's antihero. Sal idolizes him, although many are puzzled why. Dean had a rough childhood. He was raised by an alcoholic "bum" father who took his young son on the road and failed to shield him from life's ugliness. As an adult, Dean is obsessed with finding his father again and often looks for him on the road. Dean is a con man, stealing money, cars, and women. He drinks heavily and tries to elevate his thoughts through drugs and sex. He has little formal education but desperately wants to be an intellectual. Dean hits the road as recklessly as he lives his life, never caring about consequences. He has three different wives and doesn't remain faithful to any of them. At the end of the novel, he is an outsider, drug addled, and lonely.