on Writers in the Storm blog:
Create unique character voices by varying how they communicate with other characters.
I’m one of those writers who needs to put my characters through a first draft before I figure out who they really are. Tossing them into trouble and watching how they wrangle their way out of it helps me get to know them. Their dialogue and voices are usually interchangeable at first. It’s more about what they say than how they say it, or even why they say it.
The voices usually come to me as I write, and by the end of the first draft, I’ve written snippets of voice that let me see and hear the characters. On draft two, I develop those snippets into fleshed-out characters.
Since I don’t hear my characters first (like many writers do), I make conscious choices about their voices, and craft them same as I do a setting or the plot. Which keeps my authorial nose out of my character’s business, and lets them be who they are—not extensions of who I am. Characters who all sound like the protagonist or the author is a common first-draft issue for a lot of writers.