Have you ever read a book and never felt like you knew the character? You often don't even finish the book. While the books you read and love, doesn't it feel like you know those people?
When a book has a hero/heroine who never changes their personality or even their mind, then they're a cardboard character. One dimensional.
What got me to thinking today about that was how I've changed over the years. Not just appearing older (and bigger - though now not quite as big - thank goodness) but how I feel about life and the people around me. When I was a kid, I wouldn't drink tea. Yeah, I know, how un-Southern of me. Well, now I love the stuff. Part of the reason was my mom put so little sugar in it, it tasted like tainted water. My mother-in-law uses a lot of sugar and that's when I fell in love with it.
You know people expect you to be the same as you were as a child, teenager or young adult. Impossible for most of us. We mature, have different experiences, learn to improve on ourselves or develop bad habits. I'm not the same person I was last year. Sure, basically I am, but still I've changed.
So if you read a book where the heroine (using a woman for an example) is kick-ass and sure of herself to the point she does no wrong, then she's cardboard, one dimensional. I like my heroines with big faults and big problems to solve. She learns new ways to deal with her problems. She's even willing to look outside the box.
The same thing for the guy. I like a guy to skirt the law if needed and not always to justify the end. That realization of needing to improve comes often after he falls in love and wants to be a better man. Maybe he doesn't know how and the heroine doesn't have to show him. He just depends on instinct, wanting to please his lady and become a better man. Don't forget, men think different than women. What he thinks is a better man might not actually fit into what the heroine "thinks" is better. But us women are flexible, we're willing to applaud the effort.
Three to four dimensional characters is what I shoot for and sometimes readers aren't willing to let them grow and become better people. I have to say if they would give them a chance, it will be so worth it.