Thank u for the laugh, ppl just be throwing out the word "narcissist" like it doesn't mean nothing anymore. Gunna need to see that psych degree to take this one seriously, brother. Even just looking up the definition of "narcissist" or "emotional narcissist" immediately pulls up descriptions that don't match Douglas's character, and if you think it does than I'm going to have to question your ability to judge character qualities.
Additionally, even if he felt compassion for monsters like that one cyclops and even the 1st demon king, he still killed them bc they were threatening the safety of people? Yeah, he messed up the sync of the hero party, but that wasn't to stop them from hurting monsters, that was because his mom died & he was suddenly afraid of anyone else getting hurt?? I just crash read ALL of this, and his moral dilemma with killing "monsters who are just living & mean no harm" has yet to actually put anyone in direct danger. So I'm very confused why you fixated on that as an example.
The only time I've seen him "force" something on someone, was his own daughter. And it was recently, when he practically told her to forgive Fanny (which imo -- it was a bit much. she shouldn't have to forgive someone who hurt her just because they were also being used. but it's also not my story so wtvr ig?????).
tl;dr, you can just say you think the main character is annoying & you don't like him

The "kill the hero after killing the demon king" reincarnation / regression trope is painted as evil but with Douglas I get it. He's the kind of person who would in the middle of battle turn his blade on you for trying to actually kill the demon king instead of subdue and talk to him.
He himself has extraordinary power, which allows him to extend personal mercy more than others. Which is fine. But then he forces that on others who are NOT as powerful as him and he cannot always protect given he is not actually immortal and omnipotent.
Our dear MC is not a compassionate and selfless hero, he is a moral coward and squeamish emotional narcissist.
Fortunately the dad / daughter vibes were nice enough to keep reading but man does he make me mad.