So, I am trying to work out the personality and backstory of one of my characters, Alyssa, a Muggle woman who hunts down and kills magical girls for a living. But I am having some trouble with coming up with a believable reason for why she goes killing magical girls in the first place.
The main motivation I want her to have when going off hunting magical girls is that she wants to be in control of her life, or at the very least know everything so that she can be prepared for whatever situation she is facing. Magical girls, as they possess all kinds of magical powers, are a danger to herself and the ones she cares about, so she wants to eliminate them all and remove that danger.
Now, as to what triggered this, I was planning to have Alyssa be involved or witness an incident, during which she comes into contact with some magical girls, and realizes that her sister is one of them. This event is such that it completely messes up with Alyssa’s organized world, and maybe somewhat harmful to her friends and her under control life. In other words, it plants in her mind that magical girls are evil, and must be dealt with. Alyssa will then start researching who these girls are, and will subsequently discover things that will only reinforce her initial idea that the only option to deal with them is to kill them all.
So, what kind of incident could I use to show to Alyssa that magical girls are evil, and how could I reinforce that idea, without her realizing that there are ‘good’ and ‘bad’ magical girls and associates, and that she would be better off trying to help out the good ones?