She had always figured something like this would happen. Well, no, not something quite this bad, but she had always assumed they would never work out, in the end. There had always been something that felt off about them. Something that felt not quite right. But she had loved him, so much, for months, thus when he finally looked her way and kissed her for the first time, she ignored the fact that instead of fireworks all she felt was embers—warm, pleasant, but nothing extraordinary. He had felt like something was missing from their relationship as well—that was why they had looked at Bossuet, Joly, and Musichetta's relationship with such interest. Since they obviously both liked each other, maybe they were just missing another person to make their lives complete, they figured.
So when they first met the gorgeous, feisty blonde, and both Eponine and Marius had been attracted to her instantly, they thought that this, this girl, was what they had been missing and they wasted no time in asking her out on a date. That first date had been wonderful. Cosette had bonded with the couple so well and they had spent dinner laughing and having heated discussions about all their favorite things. For the first time Eponine felt like, not that she completely clicked with these people, because she was the broken piece of the puzzle, glued together one too many times, destined to never fit quite right again, but she felt almost whole as she sat at that table in between a smiling girl and a blushing boy sipping wine and playing footsies under the table.
It was once they had reprised the night into the bedroom that everything went horribly wrong. Eponine had kissed Cosette first, loving the way the girl's soft lips felt against her irrevocably chapped ones. Hands glided over clothed curves, golden and russet hair tangling on the white sheets. The kisses they exchanged began sweet and grew heated and they were just as nice as Marius' kisses, even if they had a more delicate flavor to them that Eponine could not quite get used to. Once the girls broke apart, Eponine turned and kissed Marius, their lips locking in the familiar pattern they had grown accustomed to over the past months. His hands slid under her shirt, gently lifting it over her head, before he broke away to grab Cosette and kiss her for the first time.
Their lips met and suddenly, everything came crumbling down around Eponine. The air shifted as Cosette and Marius slowly kissed, taking on a heavy tone as if the world slowed for the pair as they kissed, oblivious to everything else around them, including the half naked brunette who sat, curled up on the pillows, struggling to keep the tears at bay, while she observed the way their lips fit perfectly together, hands locking as if they were meant to be clasped together for all eternity. When they broke apart, Cosette's eyes did not leave Marius' as she slowly, reverently, reached up and stroked his cheek, before kissing him again.
In that moment, Eponine knew—those two were the perfect, whole, unbroken, pieces of the puzzle—they were meant for each other. Cosette had been what was missing, but just the person that was missing from Marius' life, not Eponine's. The two did not even notice as Eponine slowly slid out of bed, put her shirt on, and slipped out of their lives. She let the tears fall as she exited Marius' apartment, gradually making her way back to her own and the bottle of vodka that would make it all go away.