Your characters must fight an inner battle
It’s common knowledge that fictional characters shouldn’t be perfect. In fact, they should deal with many flaws and weaknesses, so it’s easier for the rest of us to identify with them.
But on top of making them flawed, you have to highlight their internal conflict. We all lead invisible battles, and your characters should, too.
This will make them ten times more interesting, relatable, and worth your audience’s time.
Look at yourself and your relatives for inspiration.
Determining what inner battles your characters (main and supporting) are leading will act as a starting point to generate more ideas and interesting backstories.