Lots of craft books advise writers to construct deep back stories for the main characters in their books. I don’t disagree. But I also like to think about those character’s belief systems.
A character’s belief about themselves and their world…
Believe it or not, some people write from this place:
I am so much better
I’ll show them
They will rue the day
Pride turned sour.
You see, we have to have a certain amount of hubris to sit down…