Maryanne Fantalis wrote a great post about separating the author’s voice from the character’s. Another challenge is to make the characters sound different from one another.
As I’m writing, I listen to each character in turn. They all have their own agendas—the main character’s goal isn’t necessarily their goal. (It always drives me bonkers to read a book or see a movie in which secondary characters blithely and illogically disregard their own self-interest just to help out the protagonist.) They all have their own speech patterns and vocabularies. I’m constantly reminding myself “This one’s shy .... that one reads a lot ... this other one can’t bear to show any weakness ... that one keeps seeking approval ...” Sometimes I have a funny or powerful line that could be delivered by either of two characters, and I ask myself: Who would be more likely to say it? Which way would make the scene more effective?
I had one character (in a book as yet unpublished) who liked to see the world in mathematical, quantitative terms. He was always rating his experiences a scale of one to ten, or giving percentages. He would say, “That’s 40% likely to happen,” rather than, “It could happen, but I doubt it.” None of my other characters ever spoke that way.
Consider this passage from John Updike’s The Centaur:
Beyond, the Running Horse River reflected in its strip of black varnish the cobalt blue silently domed above. Elephant-colored gas tanks, mounted to rise and fall in cylindrical frames, guarded the city’s brick skyline: rose madder Alton, the secret city, lining the lap of its purple-green hills. The evergreen crest of Mt. Alton was a slash of black. My hand twitched, as if a brush were in it.
Can’t you just tell that the narrator is a painter? He sees the world in paint-tube colors (cobalt blue, rose madder), refers to varnish and to the “slash of black” that the mountain would be if he painted it. His urge to paint is so strong it’s essentially a reflex, making his hand twitch.
The narrator of Laurie Halse Anderson’s Speak is holding back a great secret. Her sentences are short and tight. (“My lip bleeds a little. It tastes like metal. I need to sit down.”) Her paragraphs and chapters are short and tight, reflecting how she has pulled inward. We know she is hurting, but for a long time we don’t know why. The truth will not come out easily; she has been nearly silenced.
Characters' voices are the filter through which their experiences come to us. Voice hints at who they are, how they see the world. It colors what they tell us, and how, and what they hold back.