Boys will be boys
Viorst intends for Alexander to be a pretty typical boy. She actually modeled him after her own same-named son, and doesn't hide his misbehaving, messy, mischievous side. In fact, the book actually seems to celebrate it by making Alexander so endearing through the humor he creates.
So what exactly is it that makes Alexander so boyish?
On the first page, we see a certain degree of slob-ness: he tells us that he has gum in his hair, and the illustration depicts toys strewn all over his floor, socks hanging out of his drawers, and all sorts of sports equipment lying around. Yes, Alexander also likes sports, and he has a drum on the floor, too, meaning he likes noise, energy, and all-around rambunctiousness. These are the qualities we tend to see in boys across all sorts of media.
And it's by no means a bad thing. Alexander gets into just enough trouble to make him interesting, but not so much that we judge him. For instance, he tries to pull the old "invisible castle" trick when his teacher asks what he drew for school (6). That's the same kind of slyness that endeared us to other 1970s boys like the Fonz.
Don't fret, youngsters: the typical boy is still around today. You don't have to look too far past Drake or Josh, Phinneas or Ferb, or even sidekick snowmen to see how goofy, somewhat underachieving boys capture our attentions and our collective hearts.
Alexander does come up with more than just the boyishness, though. He demonstrates the tell-tale signs of classic sibling rivalry as he witnesses his older brothers getting awesome toys and awesome sneakers and awesome teeth while he ends up with nothing.
Nothing except cavities, that is.
He's still a little kid, too, with his teddy bear by the bed, his hatred of all things gooey and romantic, and his love of a good cat cuddle at the end of the day.
In short, Alexander demonstrates a wide range of characteristics—but none of them are really surprising. He's "typical"…and that's just what Viorst wants him to be. Kids, who don't have super sophisticated repertoire of character traits in their growing brains can still identify with Alexander as a kind of archetypal kid.