Ni: Eponine looks inside herself for her dream — not to any outside influences, but her own heart. She envisions a life for herself in which Marius loves her rather than Cosette in order to escape her present circumstances. He gives her no reason to believe he’s in love with her, but still she holds to her dream and tries to make it come true. When forced with the bitter truth — that he loves Cosette — Eponine envisions what her life will be like in the future, and commits to one last action that will allow him to live on and her to die in peace.
Fe: The happiness of Marius is more important to Eponine than her own happiness; if he is content, she’ll find a way to be happy for him even if it breaks her heart. Even when Marius hurts her, Eponine still does everything he asks her to do, expecting nothing in return. She even risks her father’s wrath to protect Cosette and Valjean from her father’s thugs, simply because she loves Marius, and Marius loves Cosette.
Ti: She is rational enough to realize that her dream of Marius is something she invented for herself, rather than anything based in reality, and to accept this fact about herself. Eponine isn’t driven toward any real purpose, she merely seeks understanding. She uses creative logic to dress up as a man and pass herself off as one of the barricade boys.
Se: Eponine is extremely observant of what’s happening around her — she sees Marius and Cosette looking at one another, she notices Marius’ ring and his confrontation with his grandfather, and she sees the gun that will end Marius’ life. Eponine takes immediate action to save the man she loves.