Well, this is just sort of a short, sweet Zoe/Wash story of how they got together and whatnot, so I hope you people enjoy it.
It had taken her a while—a very long time, in fact—to finally realize what bugged her so much about him.
At first, she had thought that it was his loose, almost cocky attitude about his flying skills. Then, she had suspected his silly jokes. The most suspicious suspect had been the dinosaurs, though… but that didn't fit right because she hadn't liked him before she had learned about the dinosaurs.
Eventually Zoë had realized that it was the mustache that bothered her so very much. No matter what he said or did, it didn't seem to matter as long as he wore that stupid mustache. He could be sweet or funny or kind, but it wouldn't matter. The mustache ruined all his chances of becoming part of the crew in her eyes. He would always be an outcast as long as he wore it.
He could laugh and smile at her or make funny jokes when Mal was pulling a bullet out of her arm, but she just couldn't look at him for all he was worth. He could be fly the Firefly gracefully and elegantly, but she wouldn't look him in the eye for fear of seeing that awful thing on this face.
After time, even when he would kiss her, it bugged her and tickled against her lips. So she stopped letting him kiss her. And he would look at her in confusion, not knowing what was wrong, but all she could say to him was that she was too tired or she didn't feel like it. He seemed to get the idea that she just didn't like kissing him, though, which was the god's honest truth—as long as he wore that mustache.
Even when he confronted her on the subject, trying to get her to say it out loud, to get her to say she didn't like him and she wanted him to leave, she wouldn't look at him.
When Mal noticed the conflict between them, though, he decided to set them down in the mess to straighten things up. It was no good having a crew that didn't get along. He, Kaylee, and Jayne decided to watch on the sidelines, though, because, as soon as Mal began, they started to argue, yelling things back and forth that Mal was sure he didn't want to know.
It continued until Zoë just finally shouted for him to shut up as loud as she could before saying in a much calmer and controlled voice, "Honey, you gotta shave your mustache."
"What?" he asked, confused yet incensed by this discovery. "That's what's bothering you? It's not the dinosaurs? Or bad sex? Or even the jokes?"
She smiled at him then. "The sex is fine," she tried to assure him.
"So now it's just 'fine'?"
Mal interrupted immediately, not enjoying where this was headed, but she responded anyway, moving closer to him and saying, "It's more than just fine." And then she kissed him, right away pulling away and adding, "You gotta shave now."