Patterns arise when there’s consistency. When a pattern breaks, you take notice. Giving your characters consistency will not only make them more realized, but you can utilize a sudden break in their patterns to convey emotional or physical change. It could be a subtle personality quirk that develops, or one that disappears, or a change in behavior after a life-changing event.
For example, you might have a character who reacts to anxiety and fear by biting her fingernails at the beginning of your story. By the end of her journey, however, she’s gained confidence and her nails have grown back.