In order to write a character’s dialog correctly, I have to have a good image in my head of who he or she is. That doesn’t mean I need to know eye color and hair length and how they dress, necessarily—I’m using image metaphorically. I mean that part of the process of giving a character a personality is imagining their life and how they got to be who they are now.
This is for everyone, even walk-on characters who may have only one or two lines of dialog out of an entire novel. I’m not one of those authors who has to write all of that down before I can use the character. Walk-ons usually just pop up when I need them. I’ve put my protagonist in jail, let’s say, and I’d planned who his cellmate would be before I got to the scene, but I hadn’t thought much about any other prisoners. As I start writing the scene between the protagonist and his cellmate, the other prisoners just chimed in at appropriate parts. While I don’t know the names of any of them, I have a small sketch in my mind of each one’s personality and a bit of his or her history, too. It just blossomed as soon as I needed someone to make a humorous interjection.
That’s just the walk-ons. Supporting characters that are planned as parts of subplots have quite a bit more than that, while the main characters have even more.
Most of the backstory remains in my head and my notes. My stories tend to be character- and dialog- driven, so usually the only details about a character’s background that come up are the ones that would normally occur in conversation:
“You always have to be smarter than everyone else, don’t you?”
“There was a time when you found that endearing.”
“I grew up!”
Even without any description or names, reading that dialog tells you that these two have known each other a long time, that they used to be close (perhaps even romanticaly involved), and now they are less friendly. I may never reveal more about the past experiences between these two characters, but I know how they met, how long they were close, how they spent their time together, and how they had their falling out.
Usually I’m pretty good about not letting the backstory over shadow the current action. But not always. Especially if I get some characters together in a scene who are very talkative. The dialog can go on and on for a while, if I let them.
During re-write I always find some scenes like this, filled with a lot of interesting banter, but that I need to trim. When reading the scenes aloud, even just by myself, I can tell when they’re going on too long. Fortunately, usually it only takes a little pruning to punch up the scene and get things moving.
But sometimes that backstory includes information the reader needs, and it isn’t always clear until I get a reader’s perspective that some details I thought could be inferred weren’t obivous.
I have a couple of supporting characters I’m working with right now whose scenes I was trimming the last couple of nights. They’re both intresting characters. I’ve gotten feedback indicating readers like them. (Even though in the current novel they don’t have any scenes together, one of them had a short story of his own published a few years ago, and the other happened to be a supporting chracter in it.) But they’re only supporting characters in this tale, and the parts they have to play in the current story aren’t big enough to justify all that information.
Even though I saved the removed dialog elsewhere, it still hurts to trim it.
But when it’s too much, it has to go!