Zero is the novel's deuteragonist, the character second in importance. Zero's great-great-grandmother was Madame Zeroni, who put a curse on generations of the Yelnats family. Zero is dark-skinned and small in stature. He is quiet (in fact, he rarely speaks), and he doesn't readily reveal his thoughts, feelings, or emotions. A rare smile spreads across his entire face. Because he always hides what he's thinking and feeling, and because he keeps to himself, people assume Zero is stupid, but he isn't. He is quite intelligent and is particularly good in math. Zero watches Stanley write letters to his mother, and, finally, when he thinks he can trust Stanley, Zero admits that he can't read or write. He asks Stanley to teach him. Zero becomes frustrated when the Warden forbids Stanley to teach him, and Zero runs away. When Stanley finds Zero in the desert, they become loyal friends. Zero reveals that his name is Hector Zeroni, that he has been homeless for most of his life, and that he has no family. He is a "ward of the state." He told Stanley that his mother used to sing him a lullaby similar to the one Stanley knows, and he admits that he was the one who stole Clyde Livingston's sneakers. He was sent to Camp Green Lake because he'd stolen a pair of sneakers from a store the day after he'd taken Clyde Livingston's sneakers.
After finding the suitcase belonging to Stanley's great-grandfather, Zero used some of his money (which amounted to almost a million dollars) to hire private investigators to find his mother. The investigators succeed, and Zero and his mother are reunited.
