Betrayal
Betrayal and duplicity are major themes in this novel. When Artemis shows the C Cube to Jon Spiro, Spiro hoodwinks him by setting him up; the restaurant is a trap. After Spiro takes the Cube, Artemis and the fairies hatch a plan to catch him; Artemis invites him to launch a heist with him, intending to betray his trust and let the police arrest him. Spiro himself accepts, planning to use the opportunity to capture Artemis instead. Betrayal after betrayal occurs until Spiro lands himself in prison, and Artemis engages in one last breach of trust by preventing the fairies from wiping his memory.
Memory
Speaking of memory, it is another major element in the novel. The fairies have the technology to "mind-wipe" people to erase their memory of ever having seen a fairy or any kind of magic. The fairies agree to help Artemis retake the Cube from Spiro on the condition that he allows himself to be mind-wiped afterward. Much of the conflict in this book, therefore, is Artemis's struggle to hold on to his memories. To do so, he stores all of his memories in a gold medallion, which he gives to Mulch for safekeeping, before attempting to stop the fairies' mind-wipe by the use of special contacts. The original releases of the book also had a secret message coded inside the book, which directly asks the reader to help Artemis regain his memory.
Sacrifice
Artemis begins the book as a selfish, opportunistic crime lord, despite his young age. He seems to care about no one but himself and the gold he can obtain through illicit measures. Through the course of the book, however, he comes to realize that there are more important things than his comfort, and he begins to align with the fairy police in order to stop Jon Spiro from using the Cube to unleash havoc on the world. He chooses to take the risk of losing his own memories in order to do so, which is the first major step in his transition from antihero to hero.
