Dutch! wrote:If the characters are strong enough they'll almost write your story for you.
I'm quoting Dutch here because he's said the wisest thing in this thread.

*IF* the characters are strong enough, they'll carry the story. Their reactions to each other and to events in the story should be enough to make the plot roll along.
If that's not happening, then maybe your characters are not as interesting as you think they are. They're your children, so of course you love them, but try to be honest and measure how useful they really are in furthering your plot.
You could scrap it all and start over. But if the characters are weak, you'll end up in the same situation.
What I'd suggest is to give your characters new things to which they should react. New characters can serve as a foil for your existing characters, making their personalities come forth. (This is the base of the old writing advice, 'When in doubt, add ninjas.'

) New events, like disaster, birth or death, can also force your characters to act and interact with others. Be cruel to them -- poke and prod them like worms under a scalpel until you start getting their honest reactions.
When you give them all this new stimuli, make sure they don't all react in the same way. You need to have their personalities diverge, to have them think and act differently. Then the plot will arise naturally as, when faced with a situation, one character will say, "Let's do this", and another will say, "No, this is what we should do." That conflict between characters is what dramatic plots are all about.