Ah, that bastard child of writers: Fan Fiction. Hey, if someone can make a bajillion dollars writing some horrid fanfic and changing a few things around, adding a little bit of bondage and a lot of horrible writing (see last post), then hell, what's so bad about it?
Why do writers sometimes feel guilty writing in someone else's world, be it Darkover, or Werewolf: The Apocalypse, or D&D? Is it because we feel like we're being lazy, not creating another world of our own?
I find fanfic to be more difficult than home-grown fiction. Why? You got someone else's rules you have to follow, someone else's lore. This means that you can't be a king of a realm, when there's already a timeline established (albeit in the original author's head). You probably can't play in the highest echelons of power because the author already did. (You can't be a bastard son of the king of North because the original author and some other readers of fanfic might think you're being presumptuous.)
But there's nothing wrong, in my opinion, with being someone a little lower who brushes with power - a servant, some farmer in a distant part of the world somewhere.
However, role playing begs for you to stretch its limits. How many of you have taken your home town and used Vampire: The Masquerade as its center of Camarilla lore, even if it's supposed to be surrounded by Sabbat packs? I know I have - and that's what the designers want. But if you're going to play in the Atlanta they designed, you're playing (writing) in that realm.
What's so wrong with that? Instead of anarchy in your writing, I think it brings things closer together, tighter. Because you're worrying about your character, not about the world. People who read the fanfic are going to be familiar with that world, and you won't have describe it. Just let the characters interact.
One thing if you're going to write fanfic: Get your lore straight. If you're writing in New World of Darkness, there's no more Gangrel. Sorry, but although they were cool and all, they don't exist. If you're writing in City of Heroes (RIP), know your heroes in the Freedom Phalanx. If you're writing in Minecraft...well, I don't know how to do that, so ask someone else.