His brother from the same litter, is black and white and about a third larger, and is as gentle as can be, he won't scratch or bite. His teeth may touch your skin, or he may lash out with his paw when you mess with him, but there is never the intent to bite and the claws are always retracted on him.
However, if you rough up the crazy one, he may go ballistic...he just gets carried away, no self control. When they are wrestling, he has less control and will bite the other one too hard, resulting in a screech...even though the black and white one could kick his butt.
Hard to believe the come from the same litter, but when you look at their markings, it is unmistakable: 
My wife picked them up a few years ago, and I am grateful to her. My job can be stressful, and it is nice when I come home and they appear to me when I walk in and are very dog-like. They keep my blood pressure down!