|Step into a scene with backstory|
The subject of missing links came up while I was editing and early chapter in a novel. A new character appeared at the start of the chapter, but without much context. Once I revised the scene to create a more concrete setting, I realized I wanted to know more about this new character. It's like introducing two people you hope will hit it off. Pretty hard to do unless you know them both well enough.
So, what do you do when you realize you lack backstory for a character? One approach blends two techniques: Stephen King's imagining your way into a story and Robert Olen Butler's dreamstorming (see the Resources section at the end). In essence, if you don't have a ton of time to write an extensive character study, or if you already have and just need to round out your character, try this. Before you write the chapter, write a scene that involves the character and some facet of his or her past that impacts this section of the current story. But even before you pen to paper or fingertip to keyboard, imagine the possibilities.
Tip: Select a chapter where a new character is introduced. Ask yourself what you want to convey about the person in the context of the current chapter that will allow you to reveal the character's past and convey that to the reader. Before writing let your imagination roam.
Resource: For more on Stephen King's technique, see the August 2010 issue of The Writer, an archived piece by called, "Use Imagery to Bring Your Story to Life." For more on Robert Olen Butler's dreamstorming, see From Where You Dream, Chapter 5, "A Writer Prepares."