Realistic Reincarnation.
One thing she had noticed in most self-insert stories she had read was that 1 the character always feared death unless they were suicidal, mentally disturbed, or god-like. 2 the character always accepted that lives even ones they once thought were fiction had value and the only time they really attempted to be a villain they were either misunderstood or a bad person.
She had never thought that way. First of all if you had been reincarnated it was extreme arrogance to believe this only happens to you. There is no more mystery at the other side of life. Death is simply rebirth. You may fear pain, you may fear the loss of self for there is no certainty that whatever happened to make you remember your last past life would happen again so you may be reborn without your memories next time. However there is no logical reason to believe that you will go to heaven, hell, or stop existing completely just because you die.
The first thing a self-inserted character in a reincarnation fanfiction should do is come to terms with this new world view. Not only do you not need to fear death what reason do you have to fear hurting other people? First of all there is no consequences in the beyond, second of all death does is restart life therefore if they had a shitty life they might even thank you for it if they remembered in their next life. A soul will not stop being if you kill the body it is caged in, you will not even deprive the person life experiences they may have gained because for all you know they will be reborn to live a better they there then they would have hear.
Morals have lost their meaning…in most cases. While one can accept this theatrical knowledge if would be no easy thing to act on it. Just because this makes perfect since does mean you would not feel horror and guilt if you killed someone right? It's ingrained cultural behavior to emphasize with people; yes you could slowly make yourself a sociopath to a certain degree. You could began by hurting people for no reason and learn to kill small animals with no remorse, and that could lead killing innocents or taking over the world and what not, but the question is do you really want to go though that trouble?
Most likely not, it would a pain in the ass to break yourself of all cultural normal and become something you don't need to be for any reason. Just why bother with it? In fact why bother with all the hardships and turmoil you know is going to happen. It makes much more sense so stay out of it. Most people didn't have the motivation to do great good or evil. What did knowing the plot of a story have to do with changing the world?
Nothing absolutely nothing. The only good knowing the story did was give you a choice you wouldn't have otherwise had. That's why a three year old snuck out of the house at night and stood by the water.
The story I was in was called Shingeki no Kyojin or Attack on Titan was another name for it. At three years of age I had determined the timeline of the story and I would be just the right age to try and save a bunch of kids I didn't care about if I let myself grow up, assuming that I wasn't eaten first of course.
In my first life I died at age 24 in a car wreck, in my second life I died at age 3 from drowning. Emotionally I felt nothing but relief as I gulped up icy water and slowly suffocated to death oh it wasn't pleasant, but it wasn't being eaten alive either, so let's call it a plus.