Most novels or screenplays focus on one specific story. Linda Seger, in her book, Creating a unforgettable Characters, calls this the front story. This is the actual story the writer wants to tell.
But in order to successfully tell this story we need to understand the reasons the characters act in the way they do. We need to understand the traumas, delights, and crisis of their childhood, the challenges of their adult life — we need to understand their past.
The backstory grants us two types of information leading to such an understanding.
One is of past occurrences that impact the construction of the story. Hamlet and Citizen Kane have backstories we need to understand to make sense of the tale.
Other information forms part of the character biography. This information is never directly given to us, but understanding the attitudes and values of a character through action or dialogue, allows us to predict and understand their motivation.
In Unforgiven, a deputy discusses the Sheriff’s toughness in a conversation with other deputies: “Little Bill Scared? Little Brill grew up in the streets of Kansas. Little Bill ain’t scared. He’s just no carpenter.”
Little Bill Daggett’s obsession with his roof and lack of carpentry skill reflects his failure to prevent the rain from getting into his house. It speaks to a deeper flaw — his failure to keep other elements from entering into his life; it hints at his forthcoming death, resulting from his inability to keep Will Manny out of his town.
Both types of information flows, then, serve an important function – supporting the forward story through essential details that explain character behavior.
Summary
Use backstory techniques to motivate and explain character actions.