Suppose you are reading book. You're about a third of the way in, just when it's getting good. Suddenly, you turn the page, and there's nothing. Just a blank white space. You turn the page again and see something like this:
Sorry, I got stuck. I'm not interested in these characters anymore, so I gave up and moved on to something else.
You keep flipping, hoping that it's a bad joke, but it isn't. All the other pages are blank.
How mad would you be at that author?
Why should your fanfic readers be less mad at you for abandoning your unfinished story?
Now suppose you pick up another book, get about halfway through, and you see another note. This one says:
I realized I made a mistake. I'm starting over from chapter 4. Here's what's different.
How confused would you be? How likely would you be to actually finish the book instead of just putting it down?
Do you think your fanfiction readers would be less confused?
Generally, I post my fanfics a chapter or two at a time as I write them, and I often write out of order, so that I have chunks of material from different time periods that need to be connected to one another. I'm the last person to tell you that you should complete a whole manuscript before you post anything.
So then what exactly do I mean when I say "finish your story before you put it on the internet?"
Everybody's writing process is different. Some people write detailed outlines. Some people use notecards. Some people just sit down and write and see what happens. Whatever method you use, there has to be a point where you decide whether the story is going to work and whether it's worth the effort of finishing.
If you're going to post a story to the internet, you should have enough finished that you know where the story is going. Know the major points, including the ending, and have at least a rough idea of how you're going to get there. There's no way to work out all the kinks. Stories change as they're written. Things happen along the way. If you're not sure where the story is going or you have any doubts that you can finish it, then hold off on posting it online.
As I've alluded to before, one of the biggest differences between publishing fanfiction and publishing original stories is the relationship between the author and the audience. Fanfic authors get to interact with their readers directly, sometimes for months or years and even develop friendships with them. Everyone involved in a fandom is there for fun, to share their appreciation and love for a franchise with other fans. Some fic writers seem to think those things give them an "out" when it comes to leaving stories unfinished. After all, no money is being made; fanfiction is supposed to be for fun, and "real" authors don't have instantaneous feedback from their audience. So, what's the big deal about abandoning a story, right?
I think the opposite is true. When you're doing something for pure love of doing it and you've built up an audience who's interested in your story, you're also promising your audience that you care enough to finish what you start, no matter how long it takes. In addition, your promising your audience that you know what story you're trying to tell. That means you've put in enough pre-writing to work out the biggest goofs and potential problems.
I value audience feedback from chapter to chapter. It doesn't necessarily change what I write, but it helps me make sure the story is still on track, and it's a motivator for the times when I get stuck or feel like I just don't want to continue. So I choose to post as I write.
In order to make that work, I have some personal rules:
1. If I post something online, I am committed to finishing it.
2. Once I post something, there is no "going back" or taking it out.
That means I only post after I've done my "homework" and outlined everything as much as I reasonably can, and if something needs to be changed as I go, the changes should happen in material I haven't posted yet, not in re-writes or edits of material that's already online.
It's not a perfect system. Sometimes it means I spend a long time between updates and readers get cranky. (Sorry, you guys.) Sometimes--especially with longer stories--it means I read something later and say "I wish I'd done that differently." This is where the "fanfiction is for fun" argument is actually valid. I am a perfectionist. I try to write everything to the best of my ability and I hate making mistakes. Several years ago, I realized that if fanfiction was going to stay a part of my life, I had to find a way to write it without being impossibly hard on myself.
That said, I am still learning the "finish your stuff" lesson. I took a long break (about two years) from fandom activities because I needed to get my migraines under control. I came back to several unfinished stories that I can't figure out what to do with.
My perspective on them has changed, my collaborators/resource people have moved on with their lives, and for one of them I can't find any notes. Those stories are what inspired this post, because I owe it to myself and my readers to finish what I started.
I'm not suggesting that you follow my rules. What I am suggesting is that you find some that work for you and stick with them, because nobody wants to read an unfinished story.