I was having beef¹ with a coworker a few weeks back because he got petty when I had a lot of comments on the quality of his code while reviewing it. It led us down the path of taking each other's code reviews and just being very verbose and nitpicky, just to waste as much of each other's time as possible. It was clear that the first person to back down and not take the next Code review would be the loser.
I won by playing to his natural tendency to feel guilty and self-conscious because I kept being very nice and acting like I wasn't picking up on his passive-aggressiveness. I even baked vegan cookies for the whole team because I know that he feels guilty about not being 100% vegan² and always feels very rejected when he tries to convince other people at work that vegan food is good (everyone loved the cookies).

So you can still be nice and inflict psychic damage on your enemies.

~¹ vegan beef lol~
~² I know this because his reaction to me mentioning that I'm vegan was a very guilty "ah, I'm mostly vegan as well, but y'know, mostly just at home because it's hard and people don't accept it" -- which is totally fine! I really don't judge people by what they eat, but he showed that he feels self-conscious about it which is a clear point of attack.~