The Lightning Thief is all about identity and about discovering identity. At the beginning of our narrator's tale, Percy Jackson doesn't yet know who his father is or that he has any special powers of any kind. He thinks of himself as a "bad kid," one who always gets into trouble. Over the course of the story, however, he learns things about himself that he never thought possible. What he thought were weaknesses (his dyslexia, attention deficit disorder, and knack for attracting trouble) turn out to be the markers of a demi-god, and a particularly powerful one at that. His identity is tested when he must make hard choices (i.e., deciding between staying within the safe walls of his camp or returning to NYC where monsters are sure to find him). With every choice Percy makes, he becomes more himself.
The Lightning Thief looks at two co-existing worlds: the mortal world (the world as we know it) and the immortal world (the world of the gods). Our narrator learns that there are different versions of reality in the world, and that "reality" is just the way people choose to interpret a situation. When Zeus's lightning bolt strikes a bus, the mortal world understands it as an explosion due to mechanical failure and nothing more, while the immortal world interprets the bolt as a sign of Zeus's wrath. People choose what they want to see. Our narrator straddles both the immortal and mortal worlds, and he, therefore, learns how to exist in a world of various realities.
Isolation leads to anger, hatred, and violence in The Lightning Thief. In the beginning, we learn that our narrator, Percy, is a lonely dude. He's often kicked out of schools because he's not "normal." Trouble seems to find him wherever he goes, and he has two learning disabilities (dyslexia and attention deficit disorder), making him truly feel like an outsider. Even when he has discovered that he has special powers and when he has found a place full of kids just like him, our narrator is still isolated and must stay in a cabin all by himself (thanks to his dad). When Percy feels alone in the world, he can be cold and angry. When he feels as though he has a place in the world, our he is full of courage and possibilities.
But Percy isn't the only one: Hades (the God of the Underworld) lives in loneliness underground, excluded from Mount Olympus by his brothers. The half-blood Luke resents his father, the god Hermes, for not being around or being interested in him. Isolation often results in violence, while connection and a sense of belonging often brings peace. That being said, Percy's isolation from society is also what makes him such a perceptive dude and an entertaining narrator – he notices and understands things about people in a unique way.
Amid battles with venomous monsters and angry gods, one thing becomes perfectly clear about Percy Jackson: he loves his mom more than anything. It is this love that keeps Percy strong, that motivates him to complete his quest, and that helps him to do the right thing. This love contrasts heavily with the violence that Percy experiences in The Lightning Thief, and it is what makes life worth living for him. During his quest, Percy has access to some of the most powerful weapons and magic in the history of Western Civilization, but he doesn't give a hoot about this kind of power. He is not tempted to steal anything for his own gain. He seems to understand that love (having a mother who loves him for who he is) is more important and more powerful than any master bolt or helm of darkness.
Family can be both a destructive and creative force in this novel, but no matter what, it's really important to gods, demi-gods, and mortals alike. The Greek gods are all related to each other, and they sure do have their share of family issues – there is so much tension between them that one wonders how they have survived for so long without ripping each other to shreds. Well, that's exactly the situation we find when we begin reading The Lightning Thief: the brothers Zeus, Poseidon, and Hades don't trust one another. This lack of trust nearly leads to World War III.
Similarly, we see how destructive family can be when campers like Luke feel unloved and unclaimed by their mortal parents. Even the demi-gods and gods want to feel like they are part of a family – it's not just a mortal thing. At the same time, we watch as Percy matures and grows wiser as he learns more about his father and as he realizes that his father is truly proud of him. Though his home life in Queens, NY is troubled thanks to Smelly Gabe, Percy's relationship with his mom is what makes everything OK. Their little family is what Percy lives for.
The Lightning Thief is based on the idea that the Ancient Greek gods and goddesses are still alive and still ruling the earth, sea, and sky. Mount Olympus, the home of the gods, follows the heart of Western Civilization wherever it goes and is now located on the 600th floor of the Empire State Building in New York. Our narrator, Percy, discovers that he is very much a part of this tradition, and throughout the story he learns more and more about the customs of this tradition. At the heart of this story and of Percy's quest is a plot to destroy Greek gods and goddesses. Many are beginning to question the traditions and customs that have ruled for thousands of years. Some view tradition and customs as a means of manipulating a people, while others revere tradition and customs for the way they protect and celebrate humanity and civilization. We are left wondering whether change might be a good thing or an incredibly destructive thing.
The Lightning Thief teaches us that there are more ways of communicating and of using language than one. The story helps us think outside the box and realize that there are no limits or rules when it comes to communication: if we open our minds, we can communicate with animals and gods. First of all, our narrator and protagonist extraordinaire, Percy, is dyslexic and has attention deficit disorder, which means that he has a really hard time reading and writing English and paying attention in school. This makes school REALLY hard for him, and he ends up feeling like a loser/dummy most of the time. But then he realizes that he's a demi-god, that his brain is hardwired for Ancient Greek and not modern English, and that his ability to notice lots of things at once is actually an essential skill to have when fighting a Minotaur to the death. Over the course of this story, we see characters communicate via dreams, rainbows, animals, names, green mist, riddles, and more. We often see characters communicate without words at all. Communication can happen on multiple levels at any given time, and it is often what goes unsaid or unspoken that is most important.
Many people in The Lightning Thief, both mortal and immortal, hope to deceive our narrator and others for the sake of causing chaos and violence. Lying doesn't necessarily involve saying something untrue in this novel. Often lying simply involves keeping information from someone (like the way Percy chooses not to tell Chiron everything that the Oracle told him). Percy's entire quest is built upon a deception, and so we could say that the entire novel is built upon deception. It gets tricky, though, when certain characters know how to read minds or eavesdrop on dreams. It becomes clear that lying is not a very easy task when gods and goddesses are involved.
Man, The Lightning Thief is a nail-biter. Our narrator, Percy Jackson, really can't go three feet without encountering someone or something that wants to kill him, pronto. And he's only twelve years old. The gods can get pretty mean and bloody when they want to, and they seem to want to get mean and bloody a lot. Violence is a way of life among the gods (maybe because they can never die and, therefore, don't value mortality). Even when Percy returns the master bolt to Zeus, Zeus thanks him by telling him he will spare Percy's life for the time being. This is a dog-eat-dog (or god-eat-god) world that Percy lives in. And we're not just talking about the world of the gods; the mortal world can get pretty rough too. At the end of the novel, Percy realizes that his stepdad has been hitting his mom. Violence forms the shadow that contrasts with the light in this novel, and the light is found in Percy's friendships and in his relationship with his mother.
Memory is often manipulated in the world of The Lightning Thief, and it is often redefined as well. Memory is not so much what a person recalls of the past, but mostly refers to the collective memory of a culture. The gods have been around for thousands of years, and so their memories and that culture's memory extend far back in time. This leads to all kinds of misinterpretations and manipulation of the past. It becomes clear that memory is a powerful thing, and if one could control a people's memory, one would have a lot of power over them.