Dad seemed to understand that something had changed. He'd stopped arguing and had gotten a driver's license. […] Time to grow up. (2.2)
The teen characters don't experience much emotional growth in the book, but through flashbacks, we see the growth the adult characters go through. Dad realizes that he must staring being responsible now that he's had a second kid.
He wasn't a jock or a most-likely-to-succeed sort. But he was cool. (4.27)
This is one of many instances of us being told that Adam is cool. When does the author show us Adam's coolness? What makes him cool? Is being a jock or a most-likely-to-succeed sort not cool? Why or why not?
I chose a long black skirt and a maroon short-sleeved sweater. Plain and simple. My trademark, I guess. (4.43)
Mia believes herself to be "plain and simple," and that never changes. Perhaps she is plain and simple because her parents are the opposite. She doesn't do it out of rebellion; that's just who she is.
[Mom] didn't care that people called her a b****. "It's just another word for feminist," she told me with pride. (7.30)
Mom is very confident in her rocker-chick persona, and she hopes it will rub off on her daughter. Does Mia actually take after her mother, despite the fact that she doesn't think she does?
"People believe what they want to believe." (7.39)
Kim is talking about her own and Mia's reputations as goody-goodies. They've cultivated that image, and they can take advantage of it to skip school whenever they want. So what are they actually, underneath those goody-goody personas?
She must have to work hard to keep her nails so pretty. I admire that. (8.27)
That's what you want in a nurse—a good manicure. Maybe we're supposed to think that because the nurse has good nails, it means that she's very clean and healthy and fastidious in general.
I didn't feel like I belonged with my family, and now I didn't feel like I belonged with Adam, except unlike my family, who was stuck with me, Adam had chosen me, and this I didn't understand. (9.46)
The differences in identity build tension in Mia's life, because she doesn't understand how people who are dissimilar could possibly like one another. It's not an uncommon thought for a teenager to have.
"You planning on impersonating one of us?" (9.57)
Mom says "us," clearly labeling her daughter as one of "them," that is, an uncool not-rock chick. Mia can wear a costume, but it will just be on the surface, at least as far as Mom is concerned. Okay, Mom.
"Hell, you're one of the punkest girls I know, no matter who you listen to or what you wear." (9.93)
Mia spends a lot of time telling us that Adam and her parents are cool, but here is Adam saying Mia is cool, just not using that exact word. Seriously, though, folks, what does cool mean, and why is it so important to these characters?
Even though you wouldn't think it, the cello didn't sound half bad with all those guitars. In fact, it sounded pretty amazing. (16.61)
The Labor Day party is the moment when Mia realizes she doesn't have to change herself to fit in. Her different personality, represented by the cello, can complement the personalities of others just fine.