It is always a good idea to map out the motivations that greatly influence how your characters will act and behave in any given situation. These character motives will help guide you through your story and provide believability to the actions the characters take. If you disregard a character’s motives then their actions will not mesh properly and belief can be suspended for the reader. You do not want this to happen. Luckily, a character’s motives can change and that is what needs to happen before a character can begin to behave in a completely different manner.
Generally, you will establish early on, in your story, the motivations that will guide your characters. When you need to change one of their guiding motives you then need to introduce a plot device that will make the change happen. One of the best examples of this is from a little story written by Stan Lee called Spider-man. I choose Spider-man as my example because I think most people are aware of his origin story. If you take a look at Peter Parker before the spider bite, his core motivations were school and trying to avoid Flash Thompson and the other bullies that roamed the hallways at the institution he loved. Immediately after the spider bite he was still the same guy with the same motivations. These motivations controlled how Peter would react to his new abilities. He still loved school but he could now use those abilities to beat up Flash and maybe in the process win the girl and become popular. His actions mesh with the motivations already established for the character. This is not a guy who would be motivated to wear spandex and fight crime. Stan Lee then introduced his major plot point to change Peter’s motivations. By killing Uncle Ben in a crime that Peter could have stopped we have a huge motive change and Spider-man can make sense and resonate with the reader.
When you are trying to apply a motive change to your own character, think about it first. If Stan Lee simply killed Uncle Ben, Peter would probably have sought out revenge and becoming a hero would most likely be a far stretch for him. However, by giving Peter a chance to stop the crime that directly led to his Uncle’s death, it builds in the guilt and teaches the character about great responsibility. A well thought out motive change will lead to a fantastic plot device.
Motive change is a staple in good stories and with careful construction can elevate your story, plot, and characters to amazing heights. Also keep in mind that a motive change doesn’t have to take which we often see with villains. If villains were so easy to change, our heroes would not have a very difficult journey. It is sometimes very rewarding to rehabilitate a bad character but the fun should come in how it happens. The failed attempts and the final plot device that ultimately reprograms the villain’s motivations will often come in the form of an incredible reveal that will turn your story on it’s end. This is a good thing.