As your characters go, so goes your book. Have characters that resonate with your reader and they will stay till the end to see what happens to them. Why? Because you have made them care about the character.
Readers want to see a character change, develop, learn. If you characters remain stagnant throughout the story, the reader may put the book down. Even if they continue to the end, they will not feel satisfied. It is also not likely they will recommend your book to friends.
The most satisfying change is positive. A person has a weakness. It manifests itself. The person sees they need to change. They wrestle with the change. They change for the better.
However, a character does not have to change from bad to good to be remembered. I once read a book that had such a character. I pulled for him all the way through the book. I knew he would change. He had to change! He didn’t. When I finished the book, I was deeply disappointed. I even threw the book across the room! Maybe the character did not change but, years have past since I read the story and I’ve not forgotten that character who disappointed me so much!
Hoping my characters are memorable, Gloria