Zach doesn't have meltdowns very often for me anymore. He does more for Mom because he is only with me for a weekend twice a month. Here he is not crowded by his siblings and he can play on the comp as much as he wants or swing or watch tv without having to battle for it. He also doesn't have to opportunity to get stressed here. So we get along fine any more most of the time.
At home he gets upset when Sara won't let him do what he wants. sometimes this results in a meltdown but we have found mostly that a meltdown occurs for him when he has his head set of doing something and if Sara can sit him down and get him to explain what he wants to do ( which is hard for him to do) then we can divert a meltdown. Usually it is because he can't communicate what he is thinking and he gets frustrated instantly. then he throws himself or hits himself on the head or his favorite here lately (learned from his dear little sister!) is to bite! He starts trying to put his mouth on my shoulder to express his frustration. It isn't retaliation it is getting his emotions out. If you can redirect him and let him vent some other way we are good to go! LOL I made him talk last night when he got mad and went to bite me. He was upset because the printer wouldn't do what he wanted it to do. He is still learning acceptable behavior from unacceptable behavior. I set him in his chair and made him talk to me about it. I am 5' 3" and he is just about 2" above my shoulder. He is 9 1/2.
So getting him to understand right from wrong is so important before he gets bigger.