Why do we read fan fiction? Wait, let me rephrase that – why do *I* read fan fiction? Because I like reading about Mulder and Scully (and Skinner and the Gunmen and Krycek...). That's the same reason I *write* fanfic – to write about Mulder and Scully (etc.). Not some people who are referred to as "Mulder" and "Scully" but aren't very much like the people we watch on television every Sunday night. For me, it's all about the characters.
I believe that whenever you write fanfic about Mulder and Scully and the other X-Files characters, you have an obligation as a fan to be true to the characters. But... how do you keep them in character if they're doing stuff in your story that they can't or don't do on the show? If you write MSR/RST stories, the romance part is pretty much a given on the show (IMO, anyway), but what about the sex part, especially if your story is set in an earlier season? If you write slash (whether it's Mulder/Krycek, Mulder/Skinner, Scully/Other, Langly/Byers...), how can you be true to the characters if there's been no indication on the show that they're gay or bisexual? If you write in an alternate universe (AU) or crossover stories, how important is it to keep them in character? And what about Charlie Scully?
There's a lot we know about these characters from the show. There's also a lot we *don't* know, and that's what we explore in fanfic. But to be aware of what might be in character and what might not be, you have to consider the canon of the show. ("Canon" means, essentially, "the gospel according to Chris Carter.") Sometimes it's not enough to just watch the show and try to figure it all out from there. Fortunately, there are several websites to help you. (Of course, the official site http://www.thexfiles.com/intro.html can help, but Mr. Carter and company frequently aren't that careful about continuity.)
Your first stop should be Deep Background. There, you can find character bios, a pretty good episode guide, and links to other sites to help (the FBI's site, the official Martha's Vineyard site, maps of Washington, etc.). Another good first stop is The X-Files Time Line, which has as accurate a time line as is possible with this show, where an episode can air in May and then pick up again two days later in November...
Two other great sites for backstory are The Church of X and Snark's Guide to The X-Files. Both feature episode guides and character bios, although the Church's are much more tongue-in-cheek (as the site says, it's best viewed with a sense of humor). If you're writing an MSR story, check out Kipler's Relationship Episode Guide – terribly funny as well as a good resource for picking up on all those little ScullyLooks and MulderTouches over the years.
Once you know the canon, you can begin to expand on it in your story. Again, watching the show can help you here. For instance, if you're writing a Scully/Krycek romance, check a detailed episode guide for the episodes they both appeared in, then watch their scenes together – can you detect a hint of sexual tension? If so, then you have a real, true-to-character basis for your story. If you're writing a Mulder/Skinner slash story, watch their scenes with an eye to any indication of what a sexual relationship between these two men might be like.
Beware, though, of picking up on "fanfic canon" – conventions that have become so popular in fanfic that people *think* they're show canon. One thing in particular that irritates me every time I see it is when Maggie Scully is portrayed as loving Mulder like a son. Look closely at the episodes she's appeared in. Early in the second season (during Scully's abduction), she and Mulder certainly bonded over their shared loss – but remember "One Breath," when Maggie and Melissa wanted to disconnect Scully's life support? Mulder tried to fight them, even though he had witnessed her Living Will. In "Memento Mori," Maggie was royally pissed that Mulder knew about Scully's cancer before she did. Yes, she stepped in to protect Mulder in "Wetwired," but she wasn't much nicer to him than Bill Jr. was in "Redux II."
Other examples of fanfic convention abound – Scully as the Ice Queen, Mulder as a chronic insomniac, Frohike as an ex-Marine (now *that* one puzzles me!), etc. Be aware as you write that these character elements *aren't* canon, they just seem like it.
There is evidence, however, for some level of Scully's emotional distance and Mulder's insomnia. In "Christmas Carol," Scully talks of keeping herself closed off from emotional ties – probably a result of her Navy Brat upbringing, always moving, never being able to form close friendships. In "3," Mulder says he doesn't sleep anymore, although that's more likely a result of Scully's abduction than a chronic condition – but in other episodes he does seem to be a night person, frequently calling Scully long after she's gone to bed.
What I'm getting at is this – whatever character elements you choose to develop in your story, develop them carefully. If you take them too far, they'll seem out of character.
One other HUGE thing with me – age. At the end of season seven, Scully is 36 and Mulder is approaching 39. They are mature adults, albeit with a somewhat playful side. They're not going to approach making love the same way people ten or fifteen years younger would. They're also well educated. It's unlikely they'd need to turn to pop songs to express their feelings for one another. The characters' maturity should be reflected not only in their dialogue, but in narration too, especially if your story is told from a first-person POV.
In an AU or crossover story, you might think you have a little more leeway with character. I don't think so. If your story takes place in a world where Scully never joined the FBI, she's still going to be fundamentally the same person (even though she might not have had the same experiences). If your story takes place in another time in history but is really about Mulder and Scully, the characters should be recognizable as Mulder and Scully. (Although I haven't read it, I've heard wonderful things about "Katherine of Ireland" by Jenna Tooms, archived at Chronicle X which is along these lines.) If Mulder and Scully are interacting with Buffy Summers or President Bartlet or Harmon Rabb, we should be able to recognize *all* of them. Bad example: an XF/Buffy crossover I once read in which Mulder had sex with Buffy – apart from the fact that he's twice her age, she was still in high school in this story, making the act a felony (statutory rape, whether it's consensual or not). Good example: Jori Remington's XF/JAG crossovers – while they're Mulder/Other slash stories, they're so completely in character, I believe that Mulder and Harm could've had an affair years ago.
As for Charlie Scully... since we've never met him and haven't been told much about him except that he's the youngest in the family, as far as I'm concerned, Charlie can be whoever you want him to be. I've read stories where Charlie was in the Navy like Bill Jr., and I've read stories where Charlie was gay. I even read a story recently where Charlie and his wife were both in Naval Intelligence and worked for the Smoking Man. Since there is no show canon to draw upon, Charlie Scully is a blank canvas.
Just make sure that the *other* characters are in character.
(Lara Means' stories can be found at http://www.oocities.org/larameans_2000. Hopefully, they're all in character.)
