Many people have written books on this. I’m not going to, but I will give some basics.
First, a few terms.
FMC / MMC: Female main character, male main character.
Protagonist: The most important, main, significant characters in your story. Usually you will have one protagonist. In some romances you may have two.
Antagonist: The character or thing that opposes or stymies your protagonist. This can be society, a giant shark, a big storm, a killer robot, or people. You can have many antagonists, but there should be a main antagonist.
Villain: The bad guy. Not always the same as the antagonist. In The Wizard of Oz, the villain is the Wicked Witch of the West, but she’s not the antagonist. I believe the antagonist is Dorothy herself. (Yes, you can have one character be both protag and antag; these stories are called “man against himself.”) You can have many villains.
Main, or significant characters: Your protag’s friends and allies, characters who have a lot of ‘screen time.’ Romantic interests, buddies, etc. If you’re writing a series and these characters are in many books in the series, they will have arcs as well.
Secondary characters: Not quite so important, but still relevant. They’ll probably not have arcs.
Bit characters: Someone your character interacts with once or twice; generally unimportant.
Positive Character Arc: A story in which the protagonist learns and grows. Most storis in general, all romances, and all women’s lit have positive character arcs.
Flat Character Arc: A story in which the character, through being herself, changes the world about her but doesn’t learn and grow (because she already rocks and doesn’t need to). For most of the Honor Harrington books, Honor has a flat character arc. Same with Katniss Everdeen in the Hunger Games books.
Negative Character Arc: A story in which the protagonist needs to learn and grow and does not. These are always tragedies.
Every protagonist, major antagonist and/or villain, all of your main characters, and all of your secondary characters should be at least somewhat fleshed out. I don’t mean “fifteen pages of back story and knowledge of events he experienced in third grade.” I mean some basic stuff. Specifically: what does that character want? What motivates the character? What is her goal? How will she react, presented with a dilemma?
In another article I said you need to create your characters before you start writing your book. I don’t mean you have to create every character, but you do need to have your protagonist, your antagonist, and the main characters you know you’ll need fleshed out before you begin. If, for example, you know you’re going to write a romance set in New York at an ad agency, it might be good to write up your protag’s boss, a couple coworkers, your protag’s roommate and/or best friend, and your protag’s love interest. While you write you might discover that your protag talks a lot to a particular barista; you can work on that character when you get to him.
I also advise you keep a sheet of paper for each significant character you create, so that you can list things pertinent to him. For example, if you give him brown eyes, write it down so that 100 pages later he doesn’t have green eyes.
No story is solely based on a character’s desires, though. For your protagonist, antagonist, and arguably for major villains and main characters, you will need to know a few other fundamental elements: their needs, fears, and inner wounds.
Needs, Fears, and Inner Wounds
Your character wants something desperately, which is why he’s willing to risk some part of himself to get it, possibly even his life, soul, or family. That’s what drives the plot of your story.
But your character often needs something as well, especially in a positive or negative character arc story. (In fact, you can’t write a tragedy without your protag needing something.) What your character needs drives the story element of your story.
Story: the whole shebang AND the internal, underlying character arc. One of those “one word, two meanings” things. The story is related to the theme.
So The Wizard of Oz’s plot is about four friends who set off to get things they want from the Wizard and who kill a witch along the way. The Wizard of Oz’s story is about four people who already have the things which they think they need the most, and how they come to realize they have those things.
The thing your character needs is related to his inner wound. So is the thing he wants. It works like this:
At some point in your character’s back story, something happened that affected your character fairly strongly. This is your character’s Inner Wound. Because of this, your character believes something that isn’t true, which is your character’s Lie. Your character fears the repercussions of this Lie. His goal, what he wants, is to put to bed this Fear. He thinks he can do it by getting what he wants, but in reality only the thing he needs will resolve his conflict and ease his fear.
But … but … but … wait, what?
In a series, the protagonist’s inner wound, fear, etc. won’t come out until several books through. In a book, the protag’s wound/fear shouldn’t be explicitly stated until at least after the Midpoint, because otherwise you’re going to drown your reader in back story. You want to drop enough hints that your reader is salivating to know just what happened to screw up your character so badly, but you don’t want to tell them until the last possible moment–and maybe you never tell them. That’s okay. The reader doesn’t need to know your character’s inner wound–but you do.
So: Harry Dresden. We know he’s afraid of a bunch of wizards who have put him on probation and may kill him if he violates any of the Laws of Magic. We learn this in Act 1 of Book 1 of the series. Harry is living a life of fear, even though he rarely shows it. But he thinks about it and it’s one of the things that motivates him (the other being money, i.e., not starving). It isn’t until several books into the series, when he encounters a figure from his past, that we learn that he used magic to kill his foster father, who was abusing him, and even later we discover that he was in foster care because his mother and father had both died, leaving him alone. Harry Dresden fears being alone. He will do anything for his friends, loved ones, and especially for his family–and he doesn’t even learn about who all the members of his family are until Book 12. He might have more; the series isn’t over yet.
A good rule for this sort of back story is, when in doubt, keep it out.
So you know your protag’s fear, the thing he doesn’t want to think about. He might not even realize it’s his fear. How many of us know ourselves that deeply? But it drives him. Harry Dresden wants to find the killer in Storm Front because, if he doesn’t, the White Council might decide it was him and have him executed. He’s in that position because of X events from his past, and those events, his Inner Wounds, have created his fear of being alone. Although he’s living very much alone at that moment, he doesn’t want to alienate Murphy, who is both a source of income and a potential friend. It’s complicated because it’s a series (and I’m sure that, when Butcher wrote Storm Front, Dresden’s inner life was much less complicated!) but it’s there.
Your main antagonist needs to have his/her/its inner wound, need, and fear developed as well. Often your antagonist is a mirror of your protagonist, so we see what will happen to your protagonist if he loses. You want your antagonist to be richly detailed, because that makes for a better story. Most of the antagonists in the Avatar cartoons were extremely developed and compelling characters, especially in the Korra seasons. One of the antagonists in the Aang seasons, Zuko, successfully transitioned into a protagonist through one of the best redemption arcs I have ever read or seen. Those characters stick long after you finish them. Conversely, two-dimensional antagonists aren’t interesting, which means the conflict isn’t interesting, and therefore the story isn’t interesting.
Loki is a fascinating and extremely well-developed antagonist, probably the most interesting in the MCU. That’s why he has such a following. (It doesn’t hurt that Tom Hiddleston loves playing him.) Thanos and Nebula are also well-built.
So, to reiterate:
Your character had something horrible happen in the past. This prompted him to develop some belief that isn’t true, which is his Lie. He either fears the repercussions of his Lie/Wound, or he wants to resolve those things, and that’s what prompts his goals (his Want). However, if he achieves his Want, he will either not be satisfied, or, worse, he will fail in some fashion (there’s your tragedy). Only by achieving his Need will he resolve his Wound/Lie/Fear.
In The Wizard of Oz, Dorothy is living with her aunt and uncle. She’s an orphan. Her back story is never explained, but we know she loves her dog Toto more than anything else. She fears losing him, and he bit the neighbor, who wants him put to sleep. She runs away from home. While she’s away from home, she finds out from a kindly charlatan that her aunt is very sick and may be dying. In desperate fear of losing another family member, Dorothy rushes home, only to be brained by falling debris flung about by a tornado. The whole story runs on Dorothy’s fear of losing Toto, then Auntie Em. She runs all over the place, trying to save the people she loves, trying to find something outside of herself that will solve her problems, but her strength is internal and she needs to stay put to properly use it.
One last caveat: In many cases, what the protag wants isn’t a bad thing. Often it’s a good thing. There’s nothing wrong with saving the planet or keeping the Ark from falling into the hands of the Nazis. But the protag of a positive character arc story will fail if he doesn’t achieve his Need as well. The book won’t do well. The story will feel ‘off’ and it won’t sell well. The protag can achieve a positive Want and fulfill his Need. It doesn’t have to be one or the other. But if the Want interferes with the Need, the Need must prevail, and if the character achieves both, he must achieve his Need before he can achieve his Want, or the story won’t work properly (low sales, feels ‘off,’ etc.)
Romances: a special case
Romances are very hard to write.
I’m going to use heterosexual norms here because F and M are different letters and it will reduce confusion. Romances featuring gay folks are structured the same as romances that feature straight folks.
In a romance, the FMC and MMC must be tailored to each other. Each of the two characters must contain, intrinsic to that character, whatever is needed to resolve the Fear/Lie/Inner Wound of the other. They must resolve each other, fitting together like a key and a lock.
In a standard story, your main characters can complement each other, but they don’t need to resolve each other. In a romance, there’s no wiggle room.
Many, many kinds of stories have romantic subplots, so even if you don’t write a romance, you may have a romantic story arc and you need to know this. If your series is going strong for 9 books and then in the 10th you want to get your FMC hitched, you’ll need to create a MMC tailor-made to fit her existing needs.
This does not mean the romantic interest must resolve your character’s deepest fear! For example, Mercy Thompson (written by Patricia Briggs) is most afraid of being abandoned. She gets married in one of the books. You’d think that would resolve her fear, but it hasn’t. It’s lessened it, but she still fears being abandoned by her family, which is larger than her husband. Likewise, getting married doesn’t keep Miles Vorkosigan (by Lois McMaster Bujold) from fearing that he’ll never have a place of his own in a disability-phobic society in which his father’s and grandfather’s achievements have outshone his own.
When your protagonist’s innermost fear has been resolved, the series is over. If you’re going to write a series, make certain your protag’s innermost fear is broad, hard to overcome, and can spin off many “sub-fears” that you can play with in each book’s positive character arc.
This is also why romances don’t usually have sequels; typically the romance is the story and the character’s innermost fear is resolved by the romance. Romance series usually focus on families, with Bob getting married in the first book, Frank (his brother) in the second, and so forth.
All the rest
Some people will tell you that you need to know everything there is possibly to know about a character before you write her. Some writers fill out huge questionnaires, character sheets, interview their characters, etc. You can do that if it works for you. All of that supplements what I wrote above. It doesn’t replace it. I personally don’t find it particularly important to know what color paint is on the walls in my protag’s bathroom, but you might.
Typically I develop the following for any given character:
- Weight and body shape, muscle-to-fat ratio
- Hair color, style, and texture
- Eye color and shape
- Facial and body hair
- Shape of face and hands
- Birth marks, scars, tattoos, or other distinguishing features
- Preferred clothing (what they would wear) and current clothing (what they have to wear)
- Education level (years, public or private, university names if they attended)
- Professional certifications
- Languages they speak, and to which degree
- Special skills
- Skills they’re not good at
- Dislikes and distastes
- Family size
- Birth order
- Relation to family (loving? Distanced?)
- Some significant details from their childhoods and early adulthoods
- Best friends and enemies from the past
- Items important to them
- Fighting style (fight, flight, freeze, submit; favored weapons; skill level at combat)
- Stuff specific to your story and/or genre
- Quality of home and car from childhood
- Quality of home and car in current story
For example, I have a character named Miguel Delgado Herrera. He’s a Nicaraguan Latino. He’s 5’5″ tall and weighs about 150 pounds, all muscle. He’s built solid, almost stocky, but he’s quite flexible. He’s balding, so he shaves his head. He has a mustache and van dyke. He probably has a few scars, but nothing major. No birthmarks or tattoos. He has a squarish, handsome face, a nice smile, and an easy, polite, affectionate attitude that gets him a lot of female attention, which he doesn’t want because he’s asexual and aromantic. He was educated at Nicaragua’s main university, achieved a JD there, and is licensed to practice law in Nicaragua, Guatemala, and Peru. He was a Sandinista, so he’s liberal. He speaks fluent Spanish, enough Russian to get by, and some English, but not well enough to understand slang. He’s a gymnast and a marksman with the rifle, and he drives well. He loves cooking and is very good at it. He also enjoys Sudoku.
He has an unreasoning hatred of Hondurans and blames them for the death of his first best friend, Guillermo, when he was 21 years old. His personality shifts when he has to deal with Hondurans; he becomes irritated, biting, harsh, and can even verge into being cruel.
He was born six years after his sister, one of two kids. He grew up middle-class, with both father and mother, in a loving and happy family. His parents worried when he didn’t develop an interest in girls and had him tested for hormonal problems at the doctor’s office. His peers in school made fun of him and called him gay because he exhibited no interest in girls. He developed the belief that he was defective (initial Inner Wound and Lie) and nothing his parents or sister said convinced him otherwise. Otherwise, he wanted to be an actor when he grew up.
When he was 15 years old, his sister was kidnapped out of their home. When he was 18 he defied his parents to join the Sandinistas because he wanted to avenge her kidnapping. He trained and fought as a soldier for a few years, then went to school to become a human rights lawyer. While he was a soldier his best friend was shot and killed.
When he was 25 he ran into a vampire, who infected him with semi-vampirism. (Book 1 begins here.) He joined a vampire hunting society and trained to be one of them. About two months into it, he ran into his sister, who’d been similarly infected shortly after being released from prison. Their reunion was dramatic and heartfelt.
He now hunts and fights vampires as a team with his sister and his brother-in-law. They live in a middle-class (for Nicaragua) home in the nation’s capital, and he drives a BMW because he’s a lawyer as his day job. He is a very, very messy person, but his mess is confined to his bedroom.
His current best friend is Lisette, another vampire hunter. He likes to cuddle with her because, although he’s asexual and aromantic, he still enjoys human contact. If he had to save an object from his home, it would be one of her paintings, but he doesn’t have a favorite item.
In book 1, Miguel’s Lie is that he’s defective. His inner wound is those experiences from his teen years. His Fear is that he’ll be alone. His Want is to create, save, preserve, or otherwise become an integral part of a family. His need is to realize he’s not defective. He achieves both his Want and his Need, but he doesn’t achieve his Want until he achieves his Need.
This is everything I need to write his story. Anything else accretes as I continue the series.