Identity
Percy spends much of this novel trying to come to terms with his identity. He has never felt like he fit in with others around him, and this only escalates when he discovers that he is a half-blood, a person who legitimately has two different identities as mortal and god. It is difficult for him to find a place in either world until he realizes that as a demigod, he has an identity all his own, and a place—Camp Half-Blood—where he can truly be himself.
Transformation
Characters transform over the course of any journey, becoming someone different from the person they were when they set out. This is especially true for Percy, who embarked on a hero’s quest to uncover his past and understand his new life. Percy was apprehensive and uncertain when he left Half-Blood Hill, but gained certainty and confidence in himself, his past, and his identity as a half-blood. As such, one of the major themes of this novel is transformation and discovery.
Perseverance
As a hero, Percy faces many tasks that challenge him, and at times it would be easier for him to quit. He could easily turn his back on his new life and new responsibilities and give up, but he continues to persevere, showing a true hero’s strength. Though the obstacles he faces are difficult in themselves, the real test here is mental. Percy must show his mental strength to move forward, and he passes this test with flying colors.
Friendship
Friendship is a central theme in The Lightning Thief, because Percy would never have succeeded in his quest without his friends’ help. Over and over, Annabeth and Grover used their quick thinking and cleverness to solve problems, ranging from the fight with Medusa, to the trap at the abandoned amusement park, to the challenges they encountered in the underworld. Friendship was key to Percy’s success, true proof that no hero can make it on his own.
Family
Percy has struggled with the idea of family since birth. Having never known his father, the only parental figure in his life was his mother, whom he loved very much—however, this made it harder for him to watch her get abused by Gabe, a man who was supposed to be a father figure in his life. At the end of the story, Percy meets his real father. He does not feel a familial connection to him, but he does feel happy at the idea that his father is proud of him. Percy learns at the close of the novel that family can extend beyond blood ties, when he feels strong kinship with many of the other half bloods and people who have helped him along his quest.
Loyalty
Any story of the Greek gods is fraught with loyalty struggles, and this one, despite being set in modern times, is no exception. When the threat of war occurs, people take sides, and an honorable hero will have to show loyalty to the side he supports. The Lightning Thief takes this loyalty theme and pushes it further—Percy shows loyalty not only to his father Poseidon, but also to his friends, to Chiron, and to his mother.
Deceit
The main conflict in this story revolves around the idea of deceit as characters steal and lie in order to achieve their ends. Ares lies about his intentions to Percy and his friends, Kronos remains hidden and relies on others to do his dirty work, and Luke lies and pretends that he is Percy’s friend when really he has been acting against him. Percy must uncover the truth and overcome the deceit surrounding him in order to succeed.
