When a writer develops a character they have to make sure the person is sincere. I don't mean if the character acts with deceit. Some of the most interesting story-lines come from the villain. I'm referring to the consistency of the actions and emotions of the people in the novel.
In 'Camouflage' the protagonist is the chief of a small town's police station. He takes his work seriously. The only way I can have him jeopardize his job is with an extraordinary circumstance. Anything short of that would be unnatural to his character.
If the author establishes sincere characters, their actions will make sense for their roles. The plot will move forward based in part on what the characters would naturally do.
A story can be interesting but if the characters do not feel genuine, it will fall short.