These are all part of a coherent whole and do not have to be created or decided upon in order. I often don't do any of these in the order listed:
1. Name/pronouns/nicknames
2. Physical attributes
3. Mental/Personality attributes
4. Background
5. Your Intent
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This one is the trickiest of the five. It goes hand in hand with #3 and #5, but we'll delve more into that tomorrow. .
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Essentially, just as we are shaped by our backgrounds, so too are our characters. The character's life up until the action of your story can provide the reasonings for their motivations, fears, hopes, skills, the way they talk, all kinds of things. .
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Personally, I use this as a tool for adding depth and refinement to a character. It is absolutely not necessary for you to give a detailed timeline of your characters' lives as soon as they're introduced. However, you will find them so much more lifelike if you give them memories for them to recall with fondness or anecdotes to share with someone else in confidence. .
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For practice, imagine you're a character in a story. What might the writer use from your life to give the reader a good snapshot of where you grew up, what your childhood was like, or what made you want to be a writer?