I think this is the most important part of a story, because without a believable character then nothing else will hold together.
One of my favourite characters ever doesn't even have a name, because she doesn't need one. In Daphne Du Mauriers book Rebecca, the female leads name is never revealed to us. We come to know her as the second Mrs De Winter - but nothing more than that. Thats because her character is dependent on her being overshadowed by Maximillian De winters first wife Rebecca, the story depends on us never really knowing her by her name, but by her character and her paranoia surrounding the dead wife of her bitter husband. Such clever writing, its a book I have read a hundred times and yet I only noticed that a little while ago and yet its intrinsic to the story.
You can do all kinds of things when you are trying to create a believable character, you can make list after list, you can write yourself a template questionnaire which you answer for every character you make. Its important to know your character though.
Something I do is get photos of celebrities, because sometimes you have so many characters that its hard to hold them in your head. I put their picture on the wall with a note-card and a small bio, what their motivations are and what they are looking to achieve by the end of the story. By midway through a story I have plenty of images to keep my head together and focus on who is who. Nailing your characters appearance is a huge part of moving forward - even if its just for yourself, having a vision of an actual person in your head definitely makes a difference - at least it does for me.
How does your character interact with others, are they friendly, obtuse, slutty, defensive? how? - learning that is another huge stepping stone.
Motivation - what does your character want? Everyone wants something - I want something, I don't just drift through life as a bit part to someone elses story - even your smaller characters have motivations, hopes desires and dreams - obviously if your character only has a small part to play you may not want to spend too long thinking about it, but think about it nonetheless.
Flaws - perfect characters are kind of boring, so are characters that get everything they want all the time, or lucky people, they are kind of boring too. We want to see our heroes work for it, we want them to struggle and bleed for their redemption. Make your characters flawed, Everyone has flaws - I know I do. Just like everyone encounters obstacles in life, its hard to like people who don't, its hard to relate to people who don't. We need to see our characters learn and grow. We need to be able to relate to them.
Dialogue is a topic unto itself but for the most part people speak differently, its a good way to distinguish characters from each other, some may talk a lot, some may be constantly sarcastic or mean, some may even be highly political or militant. There are so many ways to define character with dialogue, its just another tool in your arsenal, dont just rely on wordy descriptions of your character, SHOW the audience who they are by what they say and do.
Most of all its important to give your characters dimension, go people watching, make up stories for people you see in the street, sit in a cafe somewhere and observe what others do, the differences in the way they speak. Watch people. Think about your favourite characters in books or films and what it was that made them great - see if you can recreate that for your audience.
Until Next time