This quotation occurs in Part One at the end of Chapter 2, and is spoken by Margo right as Margo and Quentin begin their Orlando adventure. Not only does Margo dictate the entire plan of action for the evening, but she also assumes what Quentin’s emotions should be and dictates his responses. She is preparing Quentin for a wild and fantastic night, and she is also cementing her role as the most important thing in his life. Margo smirks self-deprecatingly when she makes the remark, but she’s also being entirely serious, and she and Quentin both know it. Margo turns Quentin’s life upside down. He spends nearly every waking moment after their night of revenge obsessively hunting for her, turning her escape into an adventure of his own.
The fundamental mistake I had always made—and that she had, in fairness, always led me to make—was this: Margo was not a miracle. She was not an adventure. She was not a fine and precious thing. She was a girl.
This quotation appears in Part Two, Chapter 15, when Quentin has been searching for Margo for several days, but hasn’t yet figured out where she is. As Quentin and his parents talk about why Chuck Parson is such a horrible bully, they suggest that he often finds it difficult to see that other people are human beings like the rest of us. It’s much easier to idealize people as gods or reduce them to animals, but it’s difficult to see people eye-to-eye. Quentin realizes that he had never really thought of Margo as someone with flaws and human emotions, but rather as a cool, perfect idol. Of course, Margo cultivated this image of herself, and Quentin helped her cultivate it by buying directly into it. But Margo, he now realizes, isn’t a goddess—she’s just another complicated human being.