Love and Sacrifice
To preserve the reputation of both families, Cordelia and James are forced into an arranged marriage at the start of the book. James and Cordelia become friends as the story progresses, and as their connection grows more difficult, they begin to feel love for one another. James and Cordelia aren't able to be together, despite their growing feelings for one another, because James still has feelings for Grace and Cordelia is determined to defend him. The concept of self-sacrifice is also covered in the book. Cordelia swears a perilous oath of loyalty to an unknown force and is prepared to put her own life in danger to save her allies. Later, as Thomas is prepared to roam London on his own, careless of any danger, Lucie and Grace sacrifice their lives to bring Jesse back from the grave. Cordelia ultimately makes the ultimate sacrifice to save James and the others and is compelled to leave without disclosing her true love to him. These people serve as examples in the book of how love and sacrifice frequently go hand in hand and how both are essential for true heroism.
Loyalty and Betrayal
Characters in the book make decisions based on their allegiance to their family, friends, and even adversaries. For instance, despite her heart being with Matthew, Cordelia chooses to wed James out of fidelity to her family and the Shadowhunter community. Because of duty and responsibility, Cordelia also takes an oath of loyalty to Lilith, a rival of Belial. In contrast, Lucie decides to stick by her pals even when they object to her attempts to revive the dead. But throughout the book, betrayal, and loyalty are also juxtaposed. James, who unwittingly causes Cordelia's pain by not being open about his actual feelings for Grace, betrays her. Thomas is also betrayed by the Merry Thieves, who stop trusting him and accuse him of being the murderer. Moreover, James and Cordelia discover that Belial has been controlling Jesse’s body, betraying their trust that he could be saved.
Friendship and Family
The strong link between Cordelia, James, and Lucie, who are ready to risk their lives to protect one another, serves as an example of friendship. The trio demonstrates the importance of friendship in maintaining secrecy. Although Cordelia maintains her promise of service to Lilith a secret from James and Lucie, Lucie and Grace keep their endeavor to bring Jesse back from the dead a secret from their friends. The group's ability to set aside their differences and work together to defend their community from the serial killer is another example of friendship in action. In the book, the idea of family is also tackled. Because of her father's alcoholism and the arranged union between Cordelia and James, Cordelia's household is in disarray. As she must choose between upholding the honor of her family and pursuing her happiness, Cordelia's commitment to her family is put to the test. Under the pull of their familial bonds, Lucie and Grace put their safety and well-being in danger to revive Jesse. Last but not least, as James discovers more about his grandfather and the sinister facets of his family history, he is forced to confront the challenging process of reconciling with his own family.
Good vs. Evil
The Shadowhunters, a group of human beings with heavenly blood who defend humanity from demonic powers, stand for good. They are courageous, devoted, and ready to risk their lives for the sake of others. Belial, a formidable demon that is hell-bent on killing the Shadowhunters and assuming control of the world, represents evil on the opposing side. He utilizes his influence to manipulate and control others, and he is prepared to go to any lengths to accomplish his objective. When Cordelia and James face Belial in the domain of demons, the conflict between good and evil comes to a head, and ultimately, the Shadowhunters win.
