While the best characters have elements of real people to make them believable, real people rarely make good fictional characters. They are often flat and full of minor contradictions that make them non-credible to a fiction reader.
No, fictional characters need to be more than real. They are often essentially an amalgam of credible traits that are easily recognizable as human 'archetypes'.
When constructing your stories, you should think not so much in terms of who your characters ARE but WHY they're in your story. You'll then be in a much better position to understand them and their purpose.
Indeed, taking this notion on board will also help you describe them well and keep their actions and motivations in check.
Because, as I've said many times, there is no story without characters - and when constructing story plots, characters come first. You should know your characters like your best friends - actually better than your best friends - BEFORE you use them to construct your story plots.
That aside, here are some pointers about the type of characters that inhabit fiction - and why they exist.
1. The Neophyte
Also known as the fool, this type of character turns up surprisingly often in fiction. He/she is generally naive or unwise at first - but usually courageous later too, and, of course, heroic.
It is their purpose to tell the story through the eyes of the reader - so that the action and plot unfold for the character at the same time as the reader.
Characters like Harry Potter, Luke Skywalker, and Bella Swann fulfill the role of the neophyte.
2. The Foil
The sidekick in fiction is almost a cliche. It can be done well - and it can be done badly.
The purpose of the foil is to balance the hero and provide the reader's perspective in a story. The sidekick is the reader's anchor in reality - someone who can help weigh the pros and cons of heroic action - and provide the voice of reason.
Sherlock Holmes' Watson, or Hercule Poirot's Hastings, even Kaye Scarpetta's Detective Marino. Also, the foil is often used to help aggrandize the hero in the eyes of the reader.
3. The Father Figure
Sometimes cast as a trusted friend, the father figure is the voice of wisdom and experience, and often a kind of mentor.
The father figure represents the hero's higher ideals at the beginning of a story and usually the mirror to the hero's journey at the end of a story. The father figure is not required to change emotionally during a story, though his persepective is more fully appreciated by the end.
Think in terms of Obi Wan Kenobi, Gandalf and Dumbledore.
4. The Mother Figure
Sometimes cast as the best friend or charming relative, the mother figure is strongly related to the archetypal Earth Mother - someone in sync with love, nature and all things good.
The mother figure exists to counter the classic 'masculine' motivations like power, justice and revenge with more nurturing elements like understanding, compassion and forgiveness.
Dan Brown's female characters, Sophie from the Da Vinci Code, Vittoria from Angels and Demons and Catherine from The Lost Symbol fulfill the mother role in his books - which is probably why Robert Langdon doesn't end up sleeping with any of them!
5. The Lover
Usually a strong motivating force for the hero's actions, though often fairly dormant in the character development front.
To be found in life threatening jeopardy, she is almost always beauty personified and worthy of supreme sacrifice. She is literally 'to die for'.
Her purpose is aspirational as well as motivational - in terms of her representation as the reason for the contest, and its ultimate prize.
Think Princess Liea and pretty much every hero's girlfriend who usually gets captured and held hostage by the bad guy...
Which brings us to:
6. The Antagonist
Psychologist Carl Jung said that the reason why we never tire of bad guys is that they represent our personal inherent fear of evil, uncertainty, danger and villainy.
The bad guy and his henchmen are the more obvious examples but other things like corrupt governmental systems, deadly viruses and natural calamities can also be used as antagonistic elements in stories.
The important thing is that the antagonist is threatening to the stability, well being and even sanity of the heroes.
Think Darth Vader, Snape, and Hannibal Lecter, to name just a few.
I hope the above examples of characters help you in your fiction.
When deciding on the stories you want to tell, it's often productive to question the roles of the characters - and fully understand their purpose in the context of archetypes - before you start plotting.
I think when you do, you'll find that your stories are stronger.
Rob Parnell's Writing Academy
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“If my doctor told me I had only six minutes to live, I wouldn't brood. I'd type a little faster.”