Until Thalia was resurrected at the end of The Sea of Monsters, which immediately precedes The Titan’s Curse, Percy was the only known human child of the Big Three. However, in this installment in the series, Thalia and Percy share the spotlight but do not always get along. Thalia dislikes Percy’s tendency to run into battle, but Percy thinks that he “didn’t need to run after her to solve every problem” (14). Both are also seen as leaders within Camp Half-Blood because their parents are so powerful, once again giving them opportunities to butt heads over their approaches to each problem. As Chiron tells Percy, “[t]he difference is that you are less sure of yourself than Thalia. That could be good or bad. But one thing I can say: both of you together would be a dangerous thing,” noting that their tempestuous relationship can lead to additional trouble (102). However, because Percy ends up accompanying Thalia, Bianca, Grover, and Zoë on the quest, he and Thalia are able to improve their relationship.

Part of the duo’s resolution comes from Thalia’s decision to join the Hunters of Artemis, ensuring that she will not be the child of the prophecy that states one of the children of the Big Three will either save or destroy Olympus.