With Zoey as our first-person narrator setting the tone (a.k.a attitude) of the book, we get a lot of snark, drama, and angst. Which basically just means that she's your typical teenager—she just happens to go through some pretty atypical life changes.
For an example of snark, check out when Zoey is told by her loser step-dad that he doesn't need a sixteen-year-old explaining things to him. She thinks: "Well, he was wearing those really bad pants and that awful shirt. Clearly he did need some things explained to him by a teenager, but I didn't think it was the right time to mention his unfortunate and obvious fashion impairment" (3.18). Yup—girl brings the sass. Heck, even when she's on the brink of dying from not addressing her summon to the House of Night, Zoey has an irreverent attitude toward authority. It's just how she rolls.
Zoey also has a tendency to focus on the drama of whatever's happening to her, which contributed to the book's angst-laden tone. So when she has to go to her first meal at the dining hall, she frets: "I squeezed my eyes shut tightly and hoped desperately that whatever we were eating for dinner (oh, please let there not be any blood-drinking involved) wouldn't disagree with my already screwed-up, nervous stomach" (8.90). Has anything bad happened yet? Nope—but Zoey's got her eyes set on what could go wrong.
And as if that possibility weren't glum enough, she whispers to herself: "Oh, no… it would be just my luck to get a raging case of diarrhea" (8.91). Okay, first, thanks for the TMI. Second, this gives us a sense of how Zoey's fears and anxieties cause her to overreact sometimes, and how that flavors the tone of the book. How many other literary characters can you think of that worry about diarrhea?