Theme

The last book I finished, The Titan's Curse, had the theme of sacrifice.

While the book has a very humorous tone, it is rather serious as well. Ask a fangirl about Zoë Nightshade's or Bianca di Angelo's death and they'll go on a rant while crying.

Speaking of those deaths, those are the main reason why I think a theme of this book is sacrifice.

All of the heroes in the quest were uncertain about their fate, which is a terrible feeling if you think about it. Even more so when the prophecy that caused this quest to begin states that two people on the quest will die, one in the desert and one by a parent's hand. It's a rather serious thing, which is easily masked by the humor and sarcasm in Percy's narration.

In the Hephaestus's Junkyard, which is located in a desert, the heroes were told not to touch anything.

"Things get thrown away here for a reason."

While some of the heroes picked up a few things, apparently it's okay as long as you don't hold anything for too long. Once Bianca stole an action figure, she sealed her fate as a metal giant activated. To save the other heroes on the quest, she sacrificed herself by going into the giant to mess with its controls. Unfortunately, the giant collapsed, perhaps due to her lack of knowledge on mechanics, and she lost her life.

Zoë was a different case. As more things were revealed through the story, along with a few foreshadowings, it became evident that she knew all along that she was going to be killed by her father, Atlas. She essentially sacrificed herself by going on the quest.

There are a few more hints of sacrifice aside from the deaths of certain people. For example, the skin of a Nemean Lion, which was the same as a Kevlar vest, except multiple times stronger and lighter. Percy wore it for most of the story, and in San Francisco he sacrificed it to his father in order to let his friend Grover transport the Opheotaurus all the way back to New York safely.