Not all characters enter into the story fresh and pure. Dickens had a habit of starting his books with the birth of the protagonist, but not every author goes all the way to the very beginning to introduce a character. Sometimes, they've got a past. And if you want me to know about that past, you're going to need a tried-and-true literary device: the backstory.
The Story So Far...
The story-within-a-story is a well-used writing technique. When that story is a backstory, however, you've got to be careful. Many authors create a backstory for certain characters. I do it all the time to help make them seem more real; a character with a past is much richer. But when the audience needs to know that backstory, you've got some stuff to think about. Presenting a backstory is pretty tricky business.
- Prologue: Some authors like to show the backstory right up front at the start of the book, in the prologue. This is a very efficient means of presenting the past part of the story before the real action of the plot begins, but it's been done to death. Other authors try to mix it up a little by presenting the backstory in other ways within the meat of the novel.
- Flashbacks: Looking for an easy way to time travel back in the past? Flashbacks are well-used technique for doing this. Anything's acceptable inside some italics. With a flashback, you can easily insert backstory in the form of entire scenes right into the middle of the narrative.
- Dialogue: Need to reveal some past events? Pull out a character who wasn't involved in that past and put them in a room with someone who was. Make the character start asking questions, and draw the backstory out through dialogue. This is a great way to make the reader feel like a part of the story; the character who doesn't know what's going on is easy to identify with and relate to, because I don't know this mysterious past either.
The way you present the backstory is important, but the timing is essential. The reader needs to have this information, but when? Keep a few tips in mind while you're writing it. Don't offer too many hints or draw the suspense out for too long. If you keep a reader on the string for an extended period of time and stretch their patience, eventually they will break. They'll get to a point where they no longer care about the backstory. Tease it just enough, make them wait just long enough, and reveal all.
A good backstory makes characters even more interesting, and adds another layer to the story you're telling. Use it the right way, and that story will be a lot better. Use it the wrong way, and it's only going to take the reader away from the story you want to tell.