Joon Ho is your typical bratty little brother who grows up to be the spoiled, still bratty, sullen teenager. The book doesn't just leave him as a stereotype though—it also gives us some major suggestions for his behavior.
Let's start by looking at Joon Ho's birth. Yeah we know, what can you say about a baby boy right? Try telling that to Joon Ho's parents, especially Apa who already thinks Joon Ho is way more important than Young Ju just because Joon Ho's a boy. Here, for example, is how Apa thinks of Joon Ho's future in comparison to Young Ju's:
Someday, Apa says, my son will make me proud. I can be president, Apa, I call out. Apa's eyes are back home. Pointing at me. He laughs. You are a girl, Young Ju. (10.27-29)
Clearly Apa isn't a feminist.
And because of the way Apa (and Uhmma, too) favors Joon Ho, Joon Ho does end up becoming a kid with an attitude, one who literally waves his penis around like he just doesn't care:
Joon, now that he has an audience, starts to do tricks. He waves his go-chu back and forth like a fireman hosing down a burning house. Peach Fuzz just stares. (13.43)
In fact, Joon uses this scene to show how dominant he is:
He shakes his go-chu clear of the last drops and pulls up his shorts. Peach Fuzz scratches his head and leans forward to see if the mound of bubbles has disappeared. Joon stands with his hands on his hips like he is challenging the kid to do better. (13.43-45).
Pretty pleased with ourselves, are we Joon?
What's surprising about Joon Ho is that he doesn't end up as your stereotypical high school bully—instead he becomes the silent, angry, gothy guy who draws, ditches school, and (it seems) smokes and drinks.
How does he turn out that way? There aren't exactly hard answers, but the book definitely leads you in the direction of Apa and his abusive ways. That's right—though Joon Ho starts out as Apa's golden boy, he eventually grows up and becomes a spoiled kid who doesn't do what he's told… which makes him a target for Apa's rage, too:
Apa turns as if to leave and then pivots back around. He balances on one leg and swiftly kicks Joon in the stomach. Joon never saw it. Never got to prepare his body. The mask of glass explodes into fine shards of pain, etching his face unrecognizable, old. In Joon's place stands a prune-faced grandfather, stopped, holding his stomach, unable to walk. (16.91-92)
By the way, this is all because Joon doesn't want to stop playing with his Legos and go to Gomo's house.
So imagine—how might you act toward your family (and the world) if your father were like this? Being pretty angry makes sense to us as a response.
Like Uhmma and Young Ju though, Joon's able to change his ways once Apa leaves. Sure he's still the grumbling type, but he—like Young Ju—is "ready when Uncle Tim comes by to pick [them] up for work" (29.5) at Uncle Tim's ice cream shack on the beach.
Joon also picks up a job at Kinko's after school to help pay for the Parks' new house (30.7). He becomes super responsible—and not at all like the little punk early on in the book who's willing to slap his sister over a Lego piece or call her a nerd with "no friends of [her] own" (27.39). It's a welcome change if you ask us, and we're pretty sure Uhmma and Young Ju agree.