Okay, so we have 2 people person A and person B
Person A has a weapon and wants to kill B, but then a new Person who we call "C" shows up to convice person to not do it because killing is bad or whatever.
That is not the main problem until what usually happens later which is them just dropping the weapon on the ground like idiots.
Now because Person B has a higher IQ than the age of a Libetarians dream partner, they do the most predictable thing in the entire world ans grab the weapon for themselves. Ans threatnes the other 2
Also the trope of the protagonist slaughtering dozens on unnamed goons only to spare the main villain because, "killing is bad".
... Person B then takes Person C hostage. Person B proceeds to monologe about how stupid both A and C are. Cue armor piercing lens flair and person B falls away, stricken. Person A: Just As Planned.
But then they have to get killed by a meteor or something so persons A and B can still be rewarded for their moral superiority with victory in a way that doesn't compromise or evolve their characters in any way.