These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: G Senjou No Maou
Complete Monster: Actually subverted with Maou, the Big Bad, who Wants revenge on Usami and Gonzou for ruining his family´s economy as well as putting his father in jail and for putting his mother and brother in massive debt respectively. He is implied to quit in Kanon´s route out of love for his brother, Kyousuke. Sure he´s a jerk, but he´s not cruel.
Kyousuke's former "landlord", Kanu, a violent abusive drunk who messed up Kyousuke´s life something horrid.
Moral Event Horizon: When you learn that Maou used a terrorist attack in Russia as a convenient way of killing Kaoru Mishima, Haru's mother, simply because she is the wife of the person who ruined his father's life, you will despise him, if you have not already done so when he kidnaps Tsubaki's kid brother, Hiroaki, then proceeds to corrupt the poor girl.
Villain Decay: Mephistopheles/Saijou in chapter three initially comes off as a cold but honorable right-wing extremist, later he is revealed to be more of a sociopath who is easily manipulated and controlled.