Born May 13, 1820, Gavroche Thénardier is the only son among his older sisters Éponine and Azelma, with younger siblings Pressoir and Jurges whose familial tie remains unknown to them. Due to the Thénardiers' poverty, Gavroche is sent to apprentice with a Montfermeil blacksmith.

In Montfermeil, he befriends the mistreated Cosette, showing her loyalty and compassion. He steals food to share with her and accompanies her chores. Together they adopt a stray dog, Chou Chou. Gavroche recovers a discarded potpourri sachet meant for Cosette from Fantine after Éponine deceitfully claims it, actively improving her life. He demonstrates an early moral stance against cruelty, criticizing mistreatment after playfully tossing a mouse at his sisters.

Gavroche departs Montfermeil before Cosette's adoption by Jean Valjean, staying with the kind blacksmith. His street-smart resilience emerges as he lives independently. Later in Paris, encountering homeless boys Pressoir and Jurges (unrelated in this adaptation), he declares himself their protector, providing shelter and guidance as their "older brother."

During the June 1832 uprising, Gavroche fights with the Friends of the ABC at the barricade. Shot, he survives when Chou Chou senses danger and drags him to safety. Cosette discovers him and secures medical care, leading to his recovery – a pivotal deviation from the source.

After the revolution, Valjean adopts Gavroche alongside Pressoir and Jurges. Gavroche enrolls in a school for orphans. Years later, in the epilogue, he pays respects at Valjean's grave alongside Cosette, Marius, and their daughter, integrated into their family.

Gavroche embodies wit, fearlessness, and empathy. Resourceful in hardship, he defends the vulnerable and maintains optimism. A defiant spirit fuels his strong sense of justice against injustice and poverty, driving actions from aiding Cosette to shielding Pressoir and Jurges.