Q: When is it useful to include backstory in your screenplay or novel?
A: When information from the past is needed in order to make sense of the present and future.
1. In writing backstory consider the following: Is it absolutely needed?
2. Is it economically executed?
3. Does it blend in seamlessly with the rest of the text?
Include only information that is absolutely necessary to your story.
In a chilling early scene in Inglorious Basterds, for example, we learn that the SS’s Colonel Hans Landa’s mission is to find missing Jews in the French countryside whom he suspects are being protected from by French Farmers.
Always try to deliver backstory in the most economical way.
In the same film, some of the backstory is revealed through Landa’s sinister, if well-mannered, speculation, interlaced with subtle threats to the dairy farmer’s family, that he suspects Perrier LaPadite of hiding a Jewish family under the floorboards of his farm house. The dialogue, therefore, does double duty: 1. It reveals the reason Landa is interrogating LaPadite—he is aware of the French dairy farmer’s sympathies for his one-time Jewish neighbours. 2. It increases our suspense because the backstory becomes an indispensable part of the interrogation with an immediate threat to the farmer and his family.
Backstory blends seamlessly into the tale when it surreptitiously manages to drive the plot forward—as in the above example—rather than halting it In order to reveal background information. Because it becomes part of the forward thrust, there is no interruption to the story’s relentless march towards the climax. Interest and tension is actively maintained.
Backstory works best when it helps, rather than impedes, the forward-thrust of the plot. The three principles mentioned above provide a useful checklist in this regard.