When it comes to making characters writers have two ends of a spectrum, and most fall somewhere in the middle. They can either create their characters first before even starting the novel or they can let the characters evolve as the plot plays out.
When making a character you have to have at least a vague idea about them, but some writers go all out on making their characters before they even start writing the first page. I read about one writer who draws a sketch of each character, knows what hospital they were born in, who their friends in kindergarten were, their first job, ect. That is a lot of work that will never make it into the book.
Like most things there are Pros and Cons to knowing that much detail about your character, the good thing is you don't have to break your flow when your writing and research some little detail about your character because you've done that before hand.
The little details about a character come up at the most unusual times, in MIND THIEF I wrote this sentence:
He leaned in close and inhaled the sweet scent of her light perfume.
Then had to hit the brakes, what did her light perfume smell like?
I then had to stop and research perfumes and find out what scents my character would pick out. This is the type of thing that if I had fully researched my character before hand I would know.
The bad side of knowing your character that well is you have even less objectivity when it comes to writing your scenes.
In REPOSSESSING SANITY where I did do a lot work on the main character before hand I had this little scene:
As the rest of the catering staff toiled away in the main kitchen, I made my special meal in the smaller family kitchen.
I had to sneak into the main kitchen to get a box of arugula lettuce, the largest covered serving platter in the mansion and a serving cart. No one paid any attention to me. While the meal cooked I made a lovely Lemon Garlic Vinaigrette, even though the guests probably wouldn't even taste it.
As the guests ate their entrées my heart was nearly bursting through my chest, I couldn't wait to see Gloria's face when I presented my dish to her.
They finally finished and I wheeled my cart in and stopped it right in front of Gloria's seat at the head of the table. I pulled off the cover and kept all emotion off my face as the conversation stopped.
All eyes in the room were glued to Gloria's baby on the silver platter. Lightly roasted on a bed of lettuce with an excellent Lemon Garlic Vinaigrette coating. The baby was Mr. Beals payment for Gloria's position and I'm sure the shock on her face had as much to do with knowing that Mr. Beals would be paying her a visit, as having her six month old baby boy presented to her in this manner.
“I'll inform the chef of your displeasure,” I said in my stuffiest tone and exited the dinning room. By the time the guests had gotten over their shock I was out the side door and in a new Porsche whose keys I had taken from the valet stand earlier.
I knew that my main character, Doug, had worked his way through college as a dishwasher in a four star restaurant and from that experience would know what sauce to coat an infant in. However the reader didn't know that. When one of my beta readers asked, “How come Doug knows so much about cooking?” I thought it was so obvious it was because of his former job. But I hadn't mentioned his job in the story. So something that was natural to me because I knew my character so well wasn't put in the story which could take the reader out of the action.
This is how I tend to work with my characters. I approach it like a Human Resources Manager and put out a job opening add:
Now hiring Psychopaths
Must be hard working and have an irresistible desire to kill and mutilate. Heavy manual labor involved.
Once I start writing I can fill in the little quirks of their behavior. Within the first page I hammer out their basic tone on life, that gives me their name. When they need a skill I think up a way that they acquired that. As they react with their environment I pick up little details on what they look like. As the story evolves so do my characters.
The upside to doing that is I don't leave the reader out of any thing that influenced their character as I am finding out about it at the same time.
The downside is I have to go back and rewrite things to match the information. The character I had that changed the most during a novel was Amanda my time traveling babe from AN EXTRA TOPPING OF HORROR.
She started out as Samantha and at some point changed her name. I wasn't aware of that until my 10th of so rewrite when she called herself that in the last chapter. Oops.
At first she was 5'2” and roughly 90 lbs. As the story progressed she had to do a lot of physical activity and she slowly grew taller until she was just a few inches shorter than Brian the main character.
Her age changed several times, she started out 35, then got younger and younger until at one point she was the youngest person ever nominated for a Noble Prize. She then grew older and older until she was roughly 30 years old.
She even acquired a hook shaped nose.
Another downside of letting your characters evolve through the book is I have never had a first chapter stay the first chapter.
THE GOOD AND THE BAD
If you spend a lot time before writing your book working on your characters you won't hit as many speed bumps in writing your first draft, however you are very locked into their reactions. If you do go into huge detail with them just remember you may have to change them as your book progresses.
If you let your characters evolve, be prepared for a lot of rewriting throughout the novel to have them reflect the changes.