Leonard is the novel’s protagonist and point-of-view character. He is a 300-year-old alien made of pure energy, usually existing as part of a hive mind, drifting through helium rivers, clouds, and crystal mountains. Unlike the rest of his species, Leonard has a poetic soul and a deep love for humanity, longing to experience distinctly human moments, such as eating a cheese sandwich or holding an umbrella in the rain. 

Leonard’s species has a practice of sending its inhabitants to another planet for a month to gather data and expand their minds about how other creatures live. Leonard decides to go to Earth and spends many years researching humanity. He originally plans to take the form of a human and get a job as a park ranger at Yellowstone national park. Leonard tries researching humor but struggles to fully understand that aspect of human life. Once on Earth, Leonard accidentally takes the form of a cat with a “crooked” tail and striped fur. He struggles to communicate due to the limitations of his cat body.

At the beginning of his journey, Leonard is an outsider, viewing Earth through the lens of an observer rather than a participant.