When I was writing 'You Suck,' in 2006, I constructed the diction of the book's narrator, perky Goth girl Abby Normal, from what I read on Goth blog sites.
I played Joseph in 'Joseph & The Technicolor Dreamcoat,' which was a bit silly because I am a girl. I wanted to be the narrator, but I had fun with it anyway.
If you feel that there's the author and then the character, then the book is not working. People have a habit of identifying the author with the narrator, and you can't, obviously, be all of the narrators in all of your books, or else you'd be a very strange person indeed.
When you pick up a book, everyone knows it's imaginary. You don't have to pretend it's not a book. We don't have to pretend that people don't write books. That omniscient third-person narration isn't the only way to do it. Once you're writing in the first person, then the narrator is a writer.
One of the strategies for doing first-person is to make the narrator very knowing, so that the reader is with somebody who has a take on everything they observe.
I didn't know how to kill off a character unless I was able, as a narrator, to get really complicated. Because it was a big deal. I'd never killed a character before.
Try as I might, Agatha Christie is unique. The actual writing style can't be exactly the same, so instead of trying to replicate it exactly, the way I got around it was by inventing a new narrator.
When the reader and one narrator know something the other narrator does not, the opportunities for suspense and plot development and the shifting of reader sympathies get really interesting.
