He didn't know how else to make things go back to normal. It wasn't like he could shrink himself back into being the same as before. (2.26)
Zach seems to understand that the changes he's experiencing socially are connected to his growth spurt. There's no going back.
But that seemed forever ago, and so much had happened since. He almost didn't feel like the same person. (3.17)
Yesterday, "forever ago"… same difference, right? We get the feeling that Zach would make a really melodramatic vampire.
Zach had followed this exact route many times, his finger curled in his mother's when he was little and then gripping the handlebars of his bike when he was older, and now on foot to and from school. (3.41)
You can almost feel the seasons passing in this sentence. Zach's growing up in a flash.
They were leaving home by themselves—going on a real adventure, the kind that changed you. He felt a thrill run through him. (6.30)
Change is scary, but it's also electrifying. For a brief moment at the start of his quest, Zach allows himself to feel excited about the possibilities.
Her angular face and thin eyebrows were utterly familiar, but he realized for the first time that she looked like one of those older, mysterious girls he wondered at sometimes in the mall, and that made her strange to him. (10.43)
Zach isn't the only one who's been changing: It's like Alice has been turning into another person right under his nose, too.
He'd taken it for granted that he'd be able to go back to being friends later, if he wanted, and everything would be the way he'd left it. (12.39)
Zach worries he has done irreparable damage to his friendships with Alice and Poppy. We remain optimistic about the trio's future, though—it may not be the same, but we're still thinking it will be good.
He didn't want to forget, and he wanted everyone to stop talking like it was inevitable, like it would happen whether he wanted it to or not. (14.41)
The thing about growing up is that it is inevitable. But by the end of the book, Zach realizes that it doesn't have to mean he forgets who he is.
He sat there for a long moment, breathing hard. Something had shifted, something seismic, and he needed to be still long enough to have it settle inside of him. (14.108)
Zach feels majorly changed when he hangs up from his phone conversation with his dad. Why do you think this is?
"We had this adventure together, but now we're going to go back. And I'll be the same, but you guys will keep changing." (16.114)
Poppy's scared of change, but as Zach points out, "Quests are supposed to change us" (16.115). So don't worry too much, Poppy.
"Maybe we can't play it the way we used to, but we could still tell each other what happens next." (16.120)
Zach finally realizes that while he and his friends are changing, it doesn't mean they have to stop being friends.