I love the characters in my novel, whether they're good or bad or somewhere in between. They're individuals with their own way of speaking and their own motivations. Like me, most of them will happily tootle along in the same routine, day to day, year to year. Working out what would make them change, react, break out can be a puzzle.
On Janice Hardy's Fiction University website, there is an article by writer K M Weiland on just this topic - How to Find Your Character's Breaking Point. Have a look.