Time and again ad nausea, writers are warned to avoid backstory. As it pertains to your characters a backstory is vital to his, her's, or its creation. It describes, if to no one else but you, WHY a character behaves the way they do. Generally, you won't use it, or a little sprinkled throughout the story.
When inspiration smacks the back of my head, the first thing is to write down a quick synopsis with an eye on what the main character is to accomplish (the goal). Here is an example of a story being researched for the National November Writing Month challenge coming up this November. (Write a 50,000+ word novel in 30 days).
While searching illustrations for another story, this picture popped up and just as quickly a story began to develop. A Boy, His Mule and Their Dog. “A boy living in post-Civil War, backwoods Missouri is orphaned when his mother dies of cholera. His father and older brother were killed during the war. The middle brother with whom he had a close relationship, left to join the Confederacy in Texas. There is no word of his being killed. With his mother's death, he sets out to find this brother.”
As this is based on historical facts and events, research is mandatory. A few days online found this boy would be traveling from central Missouri to Tucson, Arizona. How would he get there? The quest to answer that question brought me to Tucson and the Arizona State Museum library. It will take me further east to El Paso. I am already familiar with Missouri to Texas portion from previous travels. The Internet has provided a wealth of information and placed me in contact with historians along his travel route (the Butterfield Stagecoach Trail.)
As details come together it becomes obvious this young man is going to face challenges. That means it is time to assemble the character and a timeline by asking and answering some questions.
1. How old is he? 12
2. He became an orphan at 12 when his mother died. What happened to the father and two brothers?
3. The brother who went to Texas was not heard from so is presumed alive, so he sets out to find him.
3. How can a 12-year-old realistically travel alone to Texas (eventually to Arizona) alone?
4. He has never been further than a small town a few miles from their home. He doesn't even know which way Texas lies. He's going to need help. Who? Where?
5. By following the Butterfield Trail, it is possible to track daily movements and obstacles.
In order to accomplish the goal, it is necessary to understand the boy's past and what events prepared him for this undertaking. First of all, a 12-year-old raised on frontier American is going to have skills to help survive and succeed, like a 12-year-old will have the needed skills to survive on the streets of Detroit. And then, there will be individuals to step in when needed, but let's not make this easy.
During brainstorming, it was decided to make his father and older brother abusive—the reason for a scar on his cheek. That brings to play potentially dangerous behaviors that could undermine his efforts to achieve the goal. He is likely to distrust adult men. This would be revealed through interactions with those who want to help. (Flaw #1 – he is a product of abuse.) Having grown up under the influence of the middle brother and his mother he will have learned to be conservative. (Flaw #2 – No-nonsense, level-headed) That means he will not be needlessly foolhardy and careless with disregard for consequences, but he is a child with a child's mind and will make some poor decision. (Flaw #3 – Stubbornness.) He has one goal in mind with the determined resolve to find his brother, no matter what.
What does it mean to b e an abused child? The answer suggests behaviors like avoiding or resisting comforting, and have difficulty forming relationships--withdrawn. He will suffer from depression and anxiety. He could seek the approval of others which translates into his mind as “love,” even if those others are not “saints.” He will have nightmares (a great way to sneak in snippets of backstory.) Finally, there is some display of violent behavior (getting back for being hurt by his father and brother.)
As you see, the protagonist is becoming a “real” complex person whose makeup dictates action and reaction. Handled in appropriate ways these build empathy for him in the reader.
There are a number of web sites providing long lists of character flaws from which to choose, but don't stop research with those brief descriptors. Dig deeper to better understand the causes, actions, and ramifications of the chosen flaw. In the current story, when abuse was chosen for this character, a search to understand the repercussions of abuse provided extensive information to suggest appropriate reaction to events.
Therefore, some steps that should be taken in your story are:
1. Give the protagonist (and those closely associated in achieving or blocking the goal) flaws demonstrated through their actions.
2. Give the protagonist more than one weakness.
3. Provide a moral weakness—an inner conflict of acting contrary to one's beliefs.
4. Gradually reveal character flaws through the character's actions.
5. Show how the character has changed by the end of story.
By researching and writing an extensive backstory about a character the writer comes to know them intimately, even to entering into a symbiotic relationship. That can bring out some very powerful writing.