Characters are the integral part of any story; they drive the fiction with their choices, interactions, and reactions. Most trouble that people have when writing, where they say they can’t quite get something right, is usually a conflict between what the characters want and what the writer wants to happen in the course of the plot. This is a good thing: if your characters are coming alive and refusing to fit in the cubbyholes born of your plot, then you know that they are becoming authentic people.
Unfortunately, for the ease of writing, some authors will use what are called “stock characters”. Stock characters are usually based on classical literature and stereotypes. However, using characters in this way does not fool a reader. He can see through these people as if they were made of glass, because they are simple, rather than complex. These simple characters undermine a writer’s authority; once lost, the reader cannot trust the writer to continue the story truthfully. Even if you are writing fiction—especially if you are writing fiction—the reader expects the writer to convince the reader that what takes place in the story is important. This is what we call a page-turner.
Consider a soup from a can. You can easily mix this with a can of water or milk, and have a passable soup. This is fair enough for your extremely minor characters, the ones that have a line or two, or are in only one scene, and are not prominent in the story. But even this soup sometimes needs seasoning: a dash of salt, or pepper, or even some sugar or a can of mushrooms. That innkeeper that your adventuring characters encounter when they stop for the night doesn’t have to have only generic speech or appearance. He can have an accent, or you could spend some time describing how his filthy apron does not quite match the meticulous décor of the barroom. Note that this is brief and should not become something to spend a paragraph or two on; instead, this adds a little something more that colors the world you created just a little more vividly.
For major characters, or even recurring minor characters, this is no good. No one wants to serve canned soup to a food critic (your reader) as a main course. In this case, you would want to make something from scratch, right? But you have no idea how to build up a character from scratch. This is where stock characters can be put to use.
Just for a moment, I would like to mention that you don’t have to reach into stereotype or mythology to find a foundation to build a character from. You can also look to the people you know, or even people from the books you like, or from TV. If you want to base your character on these, though, make sure to change many of the details. Make your father the uncle. Make that female cop a male cook. Make that dark wizard a grocery cashier. Taking here and there from established fiction is not plagiarism, provided that you don’t take the character’s every mannerism, word, appearance, and name. Basing a character on an unsavory relative is also not libel, granting that you change enough so they are unrecognizable. When in doubt, mix and match.
Stock characters should be approached from the same angle as chicken stock. You don’t just drink it straight from the box/can. You add some heat to it, thereby already changing it. And even this isn’t the most common way to use chicken stock. Spices are added, or meat and vegetables, or even noodles. You can even mix it with other types of stock, like beef, vegetable, or seafood. This seasoned, heated stock can also be used in the preparation of other dishes than just soup, like a base for a sauce, stuffing, or even a seasoning in its own right for meats, potatoes, and rice.
Use stock characters in this way. Take the stereotype of a Damsel in Distress and some heat: she’s in distress because she’s the general of a losing army. Or add some spice: she’s not in distress, but instead saves someone else from distress. Mix it with some other stock: she’s the personification of some human concept, like Time, and has the powers thereof. Mix in some other ingredients: make your Damsel a mother, an executive, or a student. Use this stock as a base for an idea: it’s a Damsel in Distress, but she is a he.
All in all, this is a good way to start off a character that you don’t know well. Spend some time considering who he or she really is: trying speaking in his voice, or freewriting about her. You could also consider their role in your story, and use that to develop them from their humble origins.
Remember, it is fine to use stock characters as a foundation, but you should always make some attempt to change it and make it your own.