Bell, the protagonist and narrator of The Lion of Mars, is a curious 11-year-old boy who has grown up on Mars and tells the story through an innocent, childlike point of view. He finds the older settlers’ stories about Earth intriguing, but he loves his home and his life in the settlement. He is particularly close to Phinneus, the old farmer, whom he likes to help at the algae farm, and to his cat Leo. Bell also has a best friend, Trey, and he gets along well with the other teenagers. He is a compassionate and empathic child.

At the beginning of the story, Bell is scared of going against the rules. He believes that the people from the other settlements are dangerous, and resists his friends’ attempt to see the meteorite crash site for fear of crossing the settlement borders. However, he immediately volunteers to go and seek help from the other countries when the adults all get sick because he knows Trey is scared of going alone. Bell is driven by his love for his friends, which the reader sees when he gets scared in the tunnel and almost turns back: