Sometimes you need to step back from your writing and take a deeper look into your character’s and their story so they do not appear flat on the page.
Ask yourself if your readers can relate to your protagonist. You need to consider who will be reading your book. It does not matter how clever, funny and charming your characters are, will the readers truly care about them. What can you do to make them care more?
Often you can relate to your readers by giving your main character a problem they can empathise with. But it is not just the hero you need to consider. You also need an enemy for your hero to battle against. Someone who is blocking their way to achieving their goals.
The antagonist in your story should appear to be everything that your protagonist is not but they must also have some good qualities as well. People are not good or evil. Your characters should have the same character traits, as the rest of humanity to give them depth. Both your hero and antagonist need to have a few bumps in the road. Life isn’t smooth. Let them both make mistakes and figure their way out of their problems.
Begin and end your story with a bang. Remember your hero needs to learn a lesson about themselves. Are they braver than they thought? Did they know more than they thought? Were they in love with the person they thought? Your characters should have some type of self-realisation.
It can be subtle. You do not have to go into a five chapter monologue on it, just give the readers some clues how they have changed.