...had a rule in my house. When my two boys hit that age where everything was a fight. I told them that I had never seen one of them go berserk on the other without provocation. So, from then on.. every time they fought, they both lost video games for 3 days . Before the first 3 days were up, they had gotten a second.. and a third... they went about a month and a half without the games.
I knew I had won one day when they were starting to escalate into that frenzy and I heard the oldest go... "Shhhhh mom's gonna hear!"... Ah.. united against a common enemy.... They are best friends to this day.
Arabian Proverb said: "The enemy of my enemy is my friend."