The times when the two boys play well together happens sporadically through out the day. It usually is a short session, maybe the most would be 20-30 minutes. Reason being, eventually they will each have their own different ideas and not being able to come to a compromise, they will end with a quarrel, sometimes yelling, crying, toys/ structure smashing....
Other times when they are happily playing together, their conspiracy gets disbanded by an adult in the house because they would have been up to some mischief, which had set them into peals of uncontrollable giggles, almost into fits of mad delight. Here the adult will expect to find something like water splashing, soap and bubbles all over the floor, including two boys rolling all over the floor, wet and slippery from all the foam. (See what I mean by a fit?)
Just earlier, both the boys were running in circles with a couple of new plastic box files mommy had bought. They were yelling our gibberish to each other, and suggesting things such as " This is how you crash the file," and "crash" goes the file on the floor or the table. Then Max had to do it: "crash it on the mirror." That obviously was the end of their fun. Mommy kept the files away, leaving a crying Max and moaning Micah to figure what to do with themselves next.
But here's the moment of very civil play the boys did two days ago. They took turns, forgave each other when an accident happened and reconstructed their castle again and again with no fuss. That was maybe a good 20 minutes of play until it was dinner time.