There's the severed leg of a dead calf in the back of my pickup that isn't getting any fresher, so I'll make it pretty short this week. Hope you'll forgive me. No, seriously. This is the sort of thing you can't make up.
Or, well, you can. And if you want to be at all memorable when you're writing game fiction, you should. There are a number of little tricks to making fiction work, and one of them is including the occasional improbable but not impossible detail that expresses how random real life is. (The calf leg's real, though. Honest.)
Why do we care about fiction in a game work in the first place, though? Some critics are inclined to say that anything that isn't a direct rule or completely "factual" setting detail is useless. They don't like fiction; sometimes they don't even like art. That's fine. Thing is, other people do. In fact, I'm inclined to say that fiction and art are not only what put us on the map way back when, our success influenced the rest of the hobby to no small degree.
Now, I'm not going to go out on a limb and talk about game fiction as literature. That's a little egotistical, though I'm always grateful for the authors who seriously study what gives fiction literary merit and attempt to put those principles to use. Most people won't have their lives changed by a full-page fiction the same way that you might get your headspace redefined by Kerouac or Austen or even a really eye-opening read of Shakespeare. But that doesn't mean that game fiction is worthless. It's definitely worth it overall. Because fiction does two things effectively: it provides immersion, and it serves as an example of play.
Immersion I don't need to talk about too much, I think. This is the binary "it either works for you or it doesn't" aspect, and it's kind of subjective. Some people really find well-done fiction to be a quick way to escape into the World of Darkness without having to get the gang together. Others can't stand the stuff, but so it goes. Generally speaking, though, good game fiction gives you a sense of being in the same room as something going on in the World of Darkness, being right there. And love it or hate it, we can't deny that it's worked out really well for us overall.
The example of play, though: that's fiction as instructor. Each bit of game fiction should describe something that could happen in the context of the setting. It's illustrative, showing you how a story might go. "What Alec Bourbon Said," the opening fiction of Changeling: The Lost, is a good example. It's not just an immersive bit of work, it's a story that shows you how a changeling might be seen by local mortals, how two changelings might interact with one another, why promises are important, and even one example of some of the outright weirdness that is particualr to that game line. (I won't spoil it if you haven't read it, though I gotta ask why not?) The elements there are all essesntially plot hooks, in their way, but they're also intended to show you how your game might go. What you could maybe expect. And yes, there's even a couple of those improbable details that I talked about earlier, like the cat's name.
Games need examples of play. In some cases that may mean showing you how the dice roll and mechanics work. In others, it might show you how roleplaying itself works out. I can honestly say that I learned a lot about roleplaying reading about the fate of Black Dougal way back in the red-box set of D&D. (The moral of that particular story is that when you die, your friends are equally likely to give you last rites or empty your backpack so they can use it to carry more treasure.)
Fiction is one of the ways of answering the question "What do I do with this game?" When you couple the ability to get an example of play with the shot at immersing your reader in the setting, you have a pretty strong tool there. Sometimes a piece may lean more toward immersion and less toward showing you something. Sometimes it might be the other way around. Things vary by author, of course. But every piece, if it's doing its job, should instruct you a little. Maybe it shows you what it feels like to invoke one of your dread supernatural powers. Maybe it shows you a cautionary tale of how your relationships might take an ugly twist. Maybe it shows you what vampires do for fun with babies. (Damnation City, I'm looking at you!) It doesn't provide rulings — that's for the actual, not-so-fictional text to do. It provides examples. And that's a handy thing to have.
Agree with my reasoning for the inclusion of fiction? Disagree? Have a favorite piece? Fire away. Always happy to hear feedback — once I've gotten that severed leg out of my life.