“Seven half-bloods shall answer the call,

To storm or fire the world must fall.

An oath to keep with a final breath,

And foes bear arms to the Doors of Death.”

The Epigraph to the final book in The Heroes of Olympus series is the prophecy that launched the demigods’ quest. As with ancient prophecies, the prophecy’s meaning isn’t manifest but must be interpreted. How the demigods interpret its meaning shapes the choices they make. In this book, Leo interprets the prophecy to mean that he (as the son of Hephaestus, symbolizing fire) and Jason (as the son of Zeus, symbolizing storm) must be involved in the quest’s completion. In this sense, the prophecy functions as a foreshadowing device.

“‘I’m guessing that’s Antinous,’ said Annabeth, ‘one of the suitors’ leaders. If I remember right, it was Odysseus who shot him through the neck with that arrow.’”

Annabeth’s observation demonstrates how Riordan weaves references from ancient myths into the novel, meaningfully integrating them into his own story. In this section, the demigods are in Ithaca gathering information. Odysseus is the titular hero of Homer’s The Odyssey—one of the oldest ancient Greek texts—who slaughters suitors who come to claim his wife and throne. Through the use of ancient narratives and mythic figures, Riordan prepares young readers to experience the original sources with familiarity and understanding.