Some People Just Have to Cause Touble

Sometimes I just don't understand. I guess its because I spend most of my time honestly being nice to people. I mean I may bitch A LOT but in the end I try and find a connection, I make it and I earnestly try to help people.
But then there is that guy.
You know the one. Out of nowhere he does something you just don't understand, that was obviously malicious. Intended as hurtfulness, just plain mean. Sure we all are guilty of the occasional ability to do this. No I dont mean you, I mean the guy that does it over and over to to point that you can see that he ENJOYS making other people upset.
Anyway, ran into this guy yesterday, and today the fallout was well for lack of a better phrase , still raining down.
He upset someone that is important to me. That to be honest makes me want to bring the hurt down on him, and I have some ammunition.
But that would make me that guy, so for now I wait, but I am not sure how much more of that crap I can take.