[ I wrote this over a month ago and then didn't post it. But what the hell. ]
Disclaimer: I am not asserting that I have never, ever once done this myself, because likely I have at some point.
All over my flist, all the time, I see people posting about the stories they are writing and/or the stories they want to write. Not just "I'm working on a long-ish TezuRyo" or "I have an idea for some angsty Sam/Daniel". But actual details about the story or the idea for the story. And I wonder why that is.
If you are putting up the idea as a reminder to yourself, why not make a private post so you are the only one who can read it? Why expose your ideas to the LJ-reading public or even just your flist?
I don't do this myself because I am pretty close with my ideas. I may discuss them with one or two people so I can get help developing them, but I don't want to describe them in public. And I confess I just can't understand why others do so.
In fact, I find it puzzling and somewhat problematic. Suppose you want to write a story about Marcus and Oliver where things aren't going that well for them. You have an idea that you think you'll work on. So you post in your LJ:
I think I'm going to write a story where Oliver's mother dies and Marcus has to be supportive but he doesn't know how to deal with Oliver's grief and they end up having trouble with their relationship.
Now, I'm zipping along, reading my flist, and I read your post. I feel uncomfortable about it for a couple of reasons:
1. It feels to me like you are claiming this idea as your own, but without having done the work of developing it first.
2. Your idea is now in my brain.
I don't want to steal other people's ideas. But sometimes I see something like that and it just sparks and I want to write about it. So then I have to either just push it out of my mind or go to the poster and beg them to let me use their idea. That puts both of us in an awkward social situation.
And what if I remember the idea but forget that it's not mine? What if two months later, I'm thinking, I'd like to write something about Marcus and Oliver where they're having trouble with their relationship -- what about if Oliver's father dies and Marcus can't cope with Oliver's grief? So I write this story, not realising the idea isn't original to me, and then post it. Meanwhile, you have either been working on your story and not finished it or not got around to it yet.
How do you feel when I post my story? It's not like I plagiarized you -- but I did use your idea, even though it wasn't intentional. What if someone calls me on it? Then I feel badly because I didn't mean to do that.
Or maybe I did. Maybe I read your idea and decided to write it myself before you could. Hey, it could happen.
What's the statue of limitations on these ideas, anyhow? I realise that it's outside of fannish etiquette to grab your Marcus/Oliver idea right off the bat. But what if a year goes by and you don't write it? Can I take it then without asking you? What about six months? Three months?
I feel like it dilutes ideas to reveal them to all and sundry before the story is written. And it creates expectation in people which you might not meet, if you drop the story or never start it.
And here's the most ranty, snarky part of all: I sometimes suspect people of posting these detailed ideas so that they can get feedback for the idea itself, without having to go to the trouble of writing the actual story.
So, aside from that reason, which I'm not asking you to cop to, I am genuinely curious as to why you post your ideas in your LJ. Please tell me, so I can understand.
And let me know if I can steal them.
Edited to add:
Something I should have clarified: I don't think that writing the same basic idea as someone else is morally wrong and, anyhow, it's inevitable that ideas will be repeated. I don't have a problem with that.
Here, though, I think there's a social issue. If I write a Marcus/Oliver story like the one I described and someone already wrote one six months ago and someone else writes one six months later, no big. But if someone on my friends list posts their idea and then I write a story using it in fairly short order, that's outside the social bounds that we set in fandom. That's what I'm talking about here. The fuzzy social rules and expectations of fandom in general and LJ in particular.
Writing the story based on your idea is not wrong, so much as it's gauche.