Character Analysis
You probably already have a pretty good idea what kind of guy Apa is—he's the bad guy in the novel because he can't figure out how to deal with his life and anger issues. So what does he do? He takes it out on his wife and kids with his fists, plus spends quality time getting drunk and philandering.
The Good Guy Inside
But that's not doing Apa total justice because there are moments in the novel when Apa is a sweet guy, like when he's the Blob who gathers the kids up in his arms Saturday morning and won't let them go. That's what makes Young Ju and Joon Ho "[h]ope and hope. Like watching the sky for snow on Christmas even though the sun shines hot all year round. Because when the Blob comes and wraps us tight in his arms, holds us so close we can hardly breathe, that is when we can finally put our arms around him" (14.21).
Plus, as Uhmma keeps reminding us, Apa used to be a "different man" (30.49), a man who could patiently and sweetly teach Young Ju how to jump into the waves.
All In the Family
So, see? Apa has a good side too. It's just that you get the feeling violence isn't exactly an unusual or un-kosher solution for Apa. After all, what can we expect when Halmoni's only response to Apa's drunken rages is this: "That Apa of yours needs a good spanking. If only your Harabugi had not passed away" (2.4)? Sure, a spanking isn't exactly a punch in the face, but Halmoni's answer is a big hint that Apa's childhood probably wasn't an easy one either, especially with Harabugi around.
Add that to his alcoholism, the stress of immigrating to America and working two dead-end jobs, the grief of missing his mother's passing and funeral… You can kind of see how Apa might be the way he is by the end of the book—someone who, after beating wife and child to a pulp and getting thrown in jail for a night, "barely glances in [their] direction" (29.2) the next day, and instead hops straight into his girlfriend's car.
The Anti-Model Minority
Apa's the cautionary tale for the whole book; he's the one who lets all of us know that the whole Asian model minority stereotype really is a myth, that for some immigrants the difficulty of failure is something too tough to handle. Apa is, as Uhmma reminds Young Ju, a "dreamer," and because Apa is a dreamer it's no wonder that by the end of the book Apa goes back to Korea.
Without a family who's willing to have him around and no solid English skills, Apa doesn't have the support or the mental toughness to make things work out in America alone. Korea's the only place left for him.