My son is four. He has a dear friend who is five. They love each other. Playing with his friend is my son’s absolute favorite thing to do. Their relationship is quite intense though. Obviously, due to their ages, their brains aren’t fully developed yet, so impulse control is hard. In addition, they are both quite strong-willed. Don’t cave in easily. Consequently, they often find themselves in intense arguments. At times, the arguments escalate to physical fights.