nightmare in high school

Nightmare the king of negativity was up to his usual antics. killing a few monsters and humans here spreading a little negativity there you know the usual. eventually though all good things must come to an end. trying to pass the time nightmare decided he would read a book. only problem being he had read every book there is in the multiverse. thousands of years of the same loop of fighting and reading in his free time caused this but this time he was desperate. his boys were exhausted and so was he so fighting some more was out of the question fortunately he had found a book he had never read before! unfortunately the one who wrote it was a lunatic, I mean who writes stories about the king of negativity as a high school student living with his brother and acting like a depressed teenager? and in gods name how could they get so many things about the king of negativity himself so wrong? why does this character who supposedly is based off of him act like an ungrateful brat one moment and then the next everything is fine through the power of friendship?