ok this might not make a lot of sense but just hear me out
yknow how sometimes people act really nice to people they don't like and its sort of supposed to be insulting
and how everyone in the fell aus are just assholes in general and sometimes are worse about things they actually like because why on earth would you admit to liking anything
and yknow how malachite and onyx guard this magic tree that has like a lot of power and shit
perhaps the villagers actually were (on a surface level) nice to Onyx. When he was a teenager it'd piss him off as it was meant to but eventually he decided that if they were going to be like that he would just. be nice. They seemed to want him to get mad, so he would just ignore all the little things they'd hide under the niceness and pretend to take it at face value.
Meanwhile Malachite got all sorts of bullshit. It wasn't as bad as most negative guardians get, but it was just as persistent and still pretty awful. and naturally he got sick of it
Fortunately for everyone else, Malachite assumed that Onyx would be totally down to kill everyone and told him his plan. Unfortunately for Malachite, he was wrong and Onyx had enough time to get the Tree and its power (but mostly its power) as far from Malachite as he could.
Raven and Pitch went through something similar, but Pitch was able to make a few actual friends and they ended up running the village. there were certainly casualties, but that kinda stopped once everyone agreed to just do what Pitch said.