Percy falls into the icy, perfectly clear headwaters of the River Elisson while still holding Iris’s filthy staff. The water begins loosening the staff’s grime, but Percy immediately feels guilty for dirtying such a pristine pool.

Elisson, the sapphire-blue river god with a severe man bun, appears and angrily identifies himself. Percy tries to invoke being Poseidon’s son, but Elisson responds with sarcasm, strips Percy’s shoes and socks off, and ejects both Percy and the staff from the pool onto a narrow ledge.

Elisson explains that Percy has broken every rule: entering without signing up, wearing shoes, using the forbidden headwaters, and arriving when demigods are never allowed. Percy notices Annabeth watching from above and tries to keep Elisson from noticing her, while Grover’s distant, weakening pipes suggest the snake distraction is becoming dangerous.

Percy attempts diplomacy by acknowledging river pollution and apologizing for entering without permission. He tries to flatter Elisson by claiming Iris admires his yoga classes, but Elisson remains skeptical and bitter about his river being damaged downstream.

When Percy offers possible favors, including help through Poseidon, Elisson twists the offer into a threat. Declaring that he has always wondered how long it would take a son of Poseidon to drown, Elisson sends a crushing surge of water over Percy.