Think of Danny as Jin's fantasy alter ego—and unlike Jin, Danny's blond and poised for popularity at his new school. How do we know this? He's just made Oliphant High's varsity basketball team and he's already got the jokey-arrogant-jock speech down. Case in point, this conversation between him and Steve, a popular varsity basketball player:
[Steve:] Hey, props on making the legendary Oliphant High varsity basketball team, kid!
[Danny:] Come on, now. We both knew it was inevitable.
[Steve:] Well, being as you're a transfer from Hughes Academy, I'd say it was anything
but inevitable. What were you scrubs called again? The "water-lilies"?
[Danny:] Oh, please. I've got a jumpshot that'll make you cry like a little sissy girl. (6.24-6.25)
See what we mean? Danny knows the stereotypical (sexist) put-down of jock-speak—calling the other guy a "sissy girl"—and he knows how to prop up his own skills, like his jumpshot.
He's also really close to being more than just close friends with Melanie, this white girl he likes, and when we first meet Danny, he's at his house studying chemistry with Melanie. He's right about to reveal how attracted he is to her, and she seems open to his advances because she replies, "'I've actually been hoping-'" (3.6-3.7) while blushing.
Seems like young love's about to happen…
And then cousin Chin-Kee arrives…
Whatever Danny was hoping to accomplish at Oliphant High—getting a girlfriend, becoming one of the popular jocks—is totally upended when Chin-Kee, with his super-Chinese self, shows up.
Chin-Kee is not subtle. He yells out (all the right) answers in Danny's classes, even in Spanish (6.8-6.19); he makes lewd comments to Melanie, like how she is "'such pletty Amellican girl wiff bountiful Amellican bosom! Must bind feet and bear Chin-Kee's children!'" (3.21); he pees into Steve's can of Coke (6.30-6.40). He dances on library tables and sings—badly—"She Bangs" by Ricky Martin. In short, Chin-Kee completely embarrasses Danny.
Danny has good reason to hate Chin-Kee: Chin-Kee really does seem to ruin Danny's chances with Melanie. In chapter three, Melanie seems ready to go for Danny, but by chapter six, Melanie's all ready to back out of a date with Danny with a let's-be-friends speech: "'I actually wanted to talk to you about that, Danny. We're good friends, and I really like being friends'" (6.59), she says. Ouch.
Now Melanie could be telling the truth of course, but we're not so sure. Why? Even though Melanie tells Danny her decision has nothing to do with Chin-Kee, she mentions: "'I never noticed it before, but your teeth kind of buck out a little'" (6.64)—a clear reference to Chin-Kee's buckteeth. So there's a pretty good chance that Melanie is letting her distaste for Chin-Kee get in the way of her relationship with Danny.
Chin-Kee isn't to blame for everything, though. We, for one, can't quite get why Danny ruins a good bro-bonding moment with Steve when, after Danny reveals his insecurities about Chin-Kee to Steve (6.75-6.81), Steve tries to comfort him by assuring him that,
"People here [at Oliphant High] aren't like that. No one ever says anything about my weight… people here are different. You'll see, heck, if anyone ever gives you trouble, I'll break his nose." (6.84-6.86)
Sweet, right? Steve seems like a cool guy—a real friend even—but Danny's reaction to Steve's offer to buy him a Coke is way out of left field. Instead of accepting Steve's friendly gesture, Danny says: "'A Coke? What, so I can pee in it?'" (6.88-6.89). While Steve's barfing (because he's just figured out the connection between his Coke and Chin-Kee's pee), Danny just walks away with a mad look on his face (6.91).
Weird, right? Danny's clearly got a defensive chip on his shoulder that's all about him and not (just) about Chin-Kee.
Where does all that defensiveness come from?
Well for one, it's pretty clear that Danny and Chin-Kee have an odd genetic bond: Danny's blond and white while Chin-Kee is obviously Chinese. How are they even related?
It's a real head-scratcher until we find out that Danny is actually Jin toward the end of chapter eight, when Yang shows Jin changing into Danny (8.130-8.136).
Knowing that Danny is actually Jin makes it clearer why Danny hates Chin-Kee so much and responds to friendly gestures (like Steve's offer to buy a Coke) with rage. Since Jin is insecure about his Chinese appearance (so much so that he tries to change his hair into the style of blond, curly-haired Greg (5.14-5.24)), he takes a lot of his insecurities out on the people around him who look Chinese—namely Wei-Chen.
This is why he rejects Wei-Chen's friendship at first and says (rudely, we might add), "'You're in America. Speak English'" (2.62). Or later (still rudely), "'This isn't Taiwan, you doof! Stop acting like such an "F.O.B."!'" (5.10). Pretty harsh, right?
And while Danny doesn't say these same kinds of things to Steve (how could he? Steve's not Chinese), Jin's rage is still in him and it tends to attack people who try to befriend him and make him feel okay about his Chinese self.
Danny doesn't want to be comfortable with his Chinese self—that's the whole point of his character. He's white on the outside for a reason; validating his Chinese origins (through Chin-Kee, through self-acceptance) would make it impossible for him to continue the fantasy of being white. Which means he'd disappear as Danny forever.
Which is, of course, what happens in the end. Danny has to disappear once he's faced with the true face of Chin-Kee, a.k.a. the Monkey King (9.41-9.45). Monkey just went through five hundred years of learning to be a monkey; do you think he'd ever let Jin get away with being a fantasy-white version of himself?
Nope—it's time for Jin to make peace with who he is, which means it's time to show Danny to the door.