brotherly rivalry

These two are either the best of friends or the most devious and underhanded antagonists I've ever seen. When left to their own devices, they can play sweetly for hours. At times, however, they are guilty of the cheapest sucker punches and nasty tricks imaginable (and that goes both ways -- Casper is more often direct in his attacks, and Linus tends to be passive-aggressive until he snaps and slugs his brother). There's no doubt that part of what makes a brother is the ability to get a reaction at will. But it's also a joy to see that they are growing to rely on each other, to be able to interact as equals.