Joli-Coeur is a monkey and a key member of Vitalis's traveling troupe. He performs alongside three dogs, Capi, Zerbino, and Dolce, in Vitalis's street shows across France, his stage presence and antics earning coins for the group. He shares a strong bond with the troupe, especially Rémi and Vitalis.

During a harsh winter journey, after wolves kill Zerbino and Dolce in a snowstorm, Joli-Coeur contracts pneumonia. Despite his illness, he attempts to perform to aid the financially struggling troupe following the other animals' loss.

To pay for Joli-Coeur's medical treatment, Vitalis and Rémi stage a performance where Vitalis sings publicly—an unusual act hinting at his past. Though they raise funds, including a gold coin, Joli-Coeur succumbs to his illness before help arrives. His death in the same snowstorm that claimed the dogs further reduces the troupe to just Rémi, Vitalis, and Capi.