—Max to Calvin
Role and Personality
Calvin's uncle appears to be somewhat younger than Calvin's father, with more hair and a vigorous attitude. He has beady eyes, stiff hair, and a bushy moustache, which make him somewhat resemble comedian and film actor Groucho Marx. His attitude toward Calvin's rambunctious behavior was more laid-back than Calvin's parents', and he appeared far less rigid in his lifestyle, being single and childless. In fact, Calvin asked if Max was in jail (to explain why he hasn't visited in a few years), his mother is outraged, while his father replied, saying "with Max, that's not a bad guess".
Despite his initial reservations (he anticipated that Calvin's uncle might be an impostor and con man), Calvin quickly warmed up to his uncle, who cared to share his fantasies by pretending that Hobbes was alive and fearsome. As a result, Calvin was considerably saddened when his uncle left and even tried to go with him.
Behind the Scenes
Bill Watterson explained in The Calvin and Hobbes Tenth Anniversary Book that Calvin's uncle was intended to be an expansionist recurring character, and had formulated ideas where the family went to go visit Calvin's uncle. However, his uncle's role was cut short because Watterson felt in the end that Max's inclusion was not a good idea. A substantial reason for this was that it was off-putting for Calvin's uncle to be unable to refer to the intentionally unnamed parents with proper names. Although Calvin's uncle created some jokes with Calvin, the purpose of his visit was also to interact with adults. Due to Watterson's insistence that the parents are unnamed, it was hard for his uncle to carry on a conversation with them. Also, the arc failed to create new material according to Watterson. The same reasoning explains why none of Calvin's other relatives appear in the strip. They too would be hard to fit in storylines with Calvin, Hobbes, and Calvin's parents.