So what's the secret of creating a great character? It helps if they're a little flawed, it makes me like them if they have problems to overcome. But the real secret isn't in how the character acts. It's how they react to the world around them. And frankly, some writers can't seem to write realistic reactions.
What Would J.K. Rowling Do?
Suppose that you were confronted by a vampire, just suppose. Pretend that you've just been given terrible news. Imagine exactly what you'd do if you were arrested.
Don't just write things down. This is not a viable way to craft a story. See yourself in this world. Envision how you would behave if all the plot twists were happening to you. Always take the time to do that. Just stop, think and imagine.
Because if you don't, your book isn't going to be very good. I can't cite any specific examples, because that would be mean, but I've read lots of books with unrealistic reactions. So I can point out some general examples of what that looks like:
- Supporting characters: Don't save the realism for the hero. Everyone in the world should act in a believable way. I once read a book about an alcoholic. This is a meaty inner conflict, and an identifiable character flaw. But in the book, so many people around the alcoholic acted bizarrely that the story was impossible to read. You wouldn't take a known addict to a bar and leave them alone, right? So why should your secondary characters behave so carelessly? And even if they do, shouldn't you explain why?
Fear: I admire bravery as much as the next reader, but there's bravery and then there's foolishness. When your character doesn't cower, get sweaty or even feel a little twinge of worry when facing that vampire (or whatever), I'm not going to believe it. And I'm very kind, so no way will other readers believe it either.
Love: Writing love may be the hardest of all book tasks. If you have never been in love, I suggest simply not writing about it.
Physical confrontation: You can write about a fight even if you haven't been in one, but be realistic. You know how the human body moves. Think about every detail of a physical altercation, and be mindful of the laws of physics and movement.
Good writing is about reaction as much as it's about action. Your characters should always behave in a real way, and react to the world around them sensibly. Fail to do this, and many readers will fail to finish reading your books.