This is your characters’ story and if they are well-conceived, they will be consistent and in their own way, predictable. Trust them to act and react according to their own values and beliefs.
The best characters have a sense of humour. Let them have fun at your expense. Forget your carefully planned outline and hold on. It’s time for the helter-skelter. Enjoy the ride.
When writing dialogue, challenge yourself to let your characters speak for themselves, in any way they must.
Find ways to free yourself up. Write their words on paper using different pens for different characters – just as Aleksandr Solzhenitsyn used to do - the elegant fountain pen for one character, the chewed Bic for another.
After you’ve given your characters a chance to empty themselves, cut and trim, combine, or pick a line or two that says it all. Often what people really mean is not what they say. Look for that tension. And remember, what people don’t say is often far more powerful than what they do say.
You may not love your characters but you do have to defend them. Our characters arise out of our need for them.
Always look for something you can identify with in each of your characters, good or bad. Always look for something honest. And then, once you have the perfect cast, the story will virtually write itself. Now the most important work is done and the fun can start.
It's time to play.
More than any other quality, contrast defines characters. By contrasting two characters, the strongest character dynamics are achieved. Almost any relational story that comes to mind, whether a romance, a partnership, or a friendship, probably contains contrasting characters.
Keep the association between characters tight. Ensure they need each other for things to work. Change the emotions of one of the characters. What piece of information (truth or secret) could cause problems?
A good story happens when you get your character down that blasted rabbit hole. The plot is just a vehicle for the characters. When they are dealing with problems, they have to reveal themselves for who they are. Just keep them moving and let them bounce off each other.
Start now. Don't worry about the past. Flashbacks should set off alarm bells that there is something not quite right with your story. Instead, think of Lewis Carroll’s ‘Alice in Wonderland’. By the end of page one Alice is down the rabbit hole.