So my protagonist is a coward at the beginning of the novel and I want her to gradually show the dark feelings that piled up due to people underestimating her. I want her to prove everyone wrong. But she can't just be afraid of a weapon at one point and then start killing the enemy the next moment. Also, how would I turn her from cheerful to gloomy and dark?
I have a similar character in my WIP. Not the coward part but I needed to start the story with a cheerful 8 y/o and end with a twenty something that had contempt with the world. She starts with a genetic disease making her grow up as an outcast, her mother dies in her pre-teen years, she gets isolated away from most of the world, her father spends all his time more interested in his career and when she finally does get a romantic relationship it's a brief one the that ends with herpes. I hope that makes her transition believable. The reader doesn't have to agree with her view of the world but maybe they will understand how she got there.
I see. I also wanted to use my plot to alter her personality. Probably the many deaths of her friends should do the trick.
Some of it depends on the POV you're using, especially if it can effectively reveal thought processes. Events that happen and her response to them...maybe building up to a point where she can't take it anymore and just needs to act, to break the cycle, for example might work. If she just 'picks up the weapon' that doesn't mean she uses it expertly or effectively, especially the first time. Sometimes even frightened people respond in violent, out of character ways once they're cornered.
Great advice! Actually the book is in third person and her friend tries to teach her to fight. My protagonist actually starts out really clumsily with the pole-axe. I find it difficult to imagine how and why she would fight despite being a coward only if she's trained.
Lot's of people throughout history went through fighting training without knowing how they would react in a real fight. There have been literally millions of cowards trained HOW to fight... doesn't mean they can actually do it. Until the day comes when it's either defend themselves or die they won't know the truth.
In addition to the above a plausible path to bravery is if you put in place events that have the protagonist value their own life/safety less, lose a bit of their responsibility, take a bravery drug (vodka works for me).
I think your transition can be really successful if you slowly show how her life events turn her darker. For instance, her change in character might begin with a glimmer of some darker emotion caused by some hurtful life event, and continue growing over time as more unbearable events occur. I think this is believable because, even "tame" or "cheerful" people are capable of dark emotions, and they are the ones who are most likely to bottle up those emotions in order to put on a happy face or "play nice". in this case, it is completely plausible that your character would reach a point where she has had enough or that she has a revelation and realizes that she can take more power into her own hands and be more aggressive. Basically, I agree with @TWErvin2. Good luck!
I'll relay how I did something like this. It may or may not be helpful. My MC starts out dark. She had a shitty upbringing, was made to feel worthless and has a very sour demeanor. As she entered adulthood she sought affection and affirmation in men but wound up being used by all of them. One eventually tries to kill her (several times) and this is when she begins to change. She reaches a point where she no longer wants to go on making the same mistakes; she is finally convinced that it is possible to do better. Instead of training her endlessly I gave her a natural talent for the shooting sports. This was important because she had no other discernible talents (this is, in fact, pointed out in the course of the story). I had to give her something to feel good about. My MC goes in the opposite direction: she becomes less dark as time and books progress (she has found her talent, and thus her inner strength) but as she grows mentally and emotionally she is also becoming a more effective killer. Now she faces a moral dilemma: become healthier but deadlier, or stop the killing but never achieve her full greatness? Changes to someone's basic character need to be rooted in a 'tipping point' or a circumstance that reasonably but remarkably has the power to really alter a character's world-view. I used a near-death experience. I don't know that a string of dead bodies need be used for a cumulative effect. I think it is more believable that a singular incident causes someone to be knocked off their equilibrium, sending them on a different trajectory.
Before getting her to start killing, show her mental portrait. What lies did she use to tell herself just to get by? When did things start to affect her? In which way? How did she get conflicted upon her previous beliefs and reactions? What were her contradictory thoughts in comparison to her previous ones? You need to show that she grows darker. She slowly recognizes the existence of her demons. That doesn't mean that she embraces them at once. There' s always an inner fight before such a drastic change. She has to get broken. She has to get convinced. And then ->What was the turning point? You know, the point where everything sums up. Things are clear now and she can't go back to be the person she used to be. The only path left for her to see, for whatever reasons, is one.
