They are a popular couple in fanfiction because their relationship in the original story is so tragic and full of unrequited love. Fanfiction writers like to explore what could have been if things had been different. For example, if Marius had noticed Eponine's love sooner.
Another one is 'Marius and Eponine: The Untold Story'. It weaves a tale that might not be in the original work, filling in the gaps about their relationship. It could have scenes where they have more private conversations, revealing their true feelings in a more in - depth way.
One possible fanfiction idea could be that Eponine and Enjolras meet in the midst of the revolutionary fervor. Eponine, who has always been on the fringes of society, is drawn to Enjolras' passion for change. Enjolras, initially seeing her as just another face in the crowd, slowly realizes her strength and tenacity. Their relationship could develop as they fight side by side for a better future. They might exchange secret glances during rallies and eventually confess their feelings in a quiet moment away from the chaos of the revolution.
One common theme is immortality. Since Marius is a vampire, his eternal life and how he copes with it is often explored. For example, he might face bouts of loneliness or have to constantly adapt to new time periods.
Eponine is a complex character. She is often seen as tragic. For one thing, she is tenacious. Despite her difficult circumstances, she holds on to her love for Marius. She is also self - sacrificing. She risks her own life to save Marius, showing her deep - seated altruism.
One plot idea could be that after getting married, they go on a secret mission together. They pose as a wealthy couple to infiltrate an aristocratic gathering and gather information for the revolution. Another idea is that Eponine discovers she has a long - lost relative who is an aristocrat, and this causes tension in their marriage as Enjolras is initially suspicious. But in the end, they work through it and use this new connection to further the revolutionary cause.
Perhaps in the fanfiction, Cosette discovers she's pregnant at a time when there are political unrests in their city. Marius is involved in some sort of movement, and he has to balance his duties towards the cause and his family. Cosette, on the other hand, is worried about the safety of their unborn child. They have to rely on their friends and each other's love to get through this tough time, and the pregnancy becomes a symbol of hope in the midst of chaos.
Another theme could be the exploration of their individual growth within the relationship. For example, how Marius becomes more understanding of Cosette's past, and how Cosette becomes more confident in their relationship. It's about how they change and adapt to each other.
Maybe some of the old foes from their past could resurface as antagonists. For example, those who were against Marius and Cosette being together in the first place might see the new baby as a way to cause trouble. They could try to spread rumors or create difficulties for the new family.