Fantine, born in 1796, dedicates her life to protecting her daughter, Cosette, after her husband’s death. Facing societal scorn as a single mother, she leaves home seeking work but is forced to entrust Cosette to the Thénardiers, opportunistic innkeepers who exploit the child while extorting escalating payments from her. Concealing her identity as a mother, Fantine adopts the alias "Monsieur Madeleine" to labor at Montreuil-sur-Mer’s black glass factory, owned by Jean Valjean. When coworkers intercept her letters and expose her secret, she is dismissed, plunging her into destitution.

Stripped of income, she sells her hair, pawns belongings, and begs to appease the Thénardiers’ demands. Tuberculosis ravages her weakened body, worsened by malnutrition and exposure. After defending herself against violent harassment, Inspector Javert arrests her, but Valjean intervenes, sheltering her in his final days. On her deathbed, she extracts Valjean’s vow to rescue Cosette—a promise he honors after her passing. Her final breath follows a stunned realization of Valjean’s past as a convict.

The anime adaptation reimagines her struggle, omitting her novelistic turn to prostitution to focus on her perseverance through grueling labor. A pendant, original to the series, symbolizes her legacy, passing from Fantine to Cosette and eventually her granddaughter. Years later, Cosette retraces her mother’s footsteps, visiting the factory and a community daycare named in Fantine’s memory, piecing together her sacrifices. In the afterlife, Fantine’s spirit joins Bishop Myriel to shepherd Valjean toward redemption, her ethereal presence affirming her enduring moral influence.

Though the novel limits Fantine’s direct bond with Cosette, the anime expands their connection through letters and flashbacks, depicting Cosette’s active reverence for her mother. These additions amplify Fantine’s posthumous impact, framing her not only as a tragic figure but as a resilient force whose love transcends death.