i’m all in with the serial killer idea although you may want to avoid making your character too violent, Episode is a pg 13 app. the only thing i don’t like is this part-
-i’m okay with it if the MC has a reason and is a very complicated person with many layers to her.
i personally think your idea is very different than what most people would consider an ideal MC it makes your story distinctive and that’s always a good quality to have 