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Ultimately audiences don't need a lot of details about most characters' history, what they do need, in order for the story to make sense and be immersive, is justifications for their actions. If a ...
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#3: Attribution notice added
Source: https://writers.stackexchange.com/a/47132 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#2: Initial revision
Ultimately audiences don't need a _lot_ of details about most characters' history, what they do need, in order for the story to make sense and be immersive, is justifications for their actions. If a character has clear (stated) motives, reasons for being in the tale and doing what they do that is enough. You as the author will generally know far more than you ever put on the page about where characters come from and their true motives. Rufus needs a reason to attach himself to the MC and the two of them need reasons to bond, backstory may form the basis for this, but equally the events of the narrative may be sufficient without a detailed history of the characters coming into it. Note that stated motives and true motives need not be the same thing, the friction between the two can be a source of dramatic tension.