|“||You keep sending me out to do your dirty work. You pick fights for no good reason, and I'm tired of dying for you. You want to fight the kid, do it yourself.||”|
Eurytion started as a herdsman for Geryon, but accepted immortality when his father Ares offered it. He instantly regretted it, because he was bound to serve Geryon for all eternity. When Hercules reached Triple G Ranch, no sooner had he landed than he was confronted by the two-headed dog, Orthrus. With one huge blow from his olive-wood club, Hercules killed the watchdog. Eurytion the herdsman came to assist Orthrus, but dealt with him the same way. After that he killed Geryon. Because Eurytion was immortal, he reformed himself and was free until Geryon also reformed, as Geryon was a monster.
It was Eurytion that suggested that Percy clean the stables in order to secure freedom for Nico, Annabeth, Tyson, and Grover, who would be sold to Kronos by Geryon if Percy didn't clean the stables by sundown. Percy cleaned the stables, but Geryon laughed and said it wasn't a binding contract and ordered Eurytion to kill them.
He refuses to kill the teenage demigods, and so Geryon proceeds to do it himself. Percy beats him, with the help of Hera, by shooting an arrow sideways through his three hearts, and then tells Eurytion how to switch the rule of command at the ranch, by getting the animals on his side. Eurytion likes that idea, and lets them all go, helping them get to Hephaestus by giving them a metal spider that led them straight through the Labyrinth to Hephaestus's forge.
Later on, when Percy returns to camp and talks with Clarisse, he noted how she sounded like Eurytion (her half-brother), "...like she'd been fighting for a thousand years and was getting tired of it."
Eurytion is a cowboy herdsman and an excellent fighter. He has a soft spot for Annabeth, and refuses to hurt her. He doesn't approve of Geryon, yet didn't do much to get rid of him.
Eurytion is large with stark white hair, a cowboy hat, and a braided white beard. Eurytion wears jeans, a "Don't Mess with Texas" t-shirt, and a denim jacket with the sleeves ripped off. He has a tattoo of crossed-swords on his right bicep. Percy describes him as a kind of "Father Time" gone redneck and totally jacked.
- Eurytion has been trained in hand-to-hand combat.
- He is very strong and swift.
- He may have some small degree of powers that Ares himself possesses.
- When Percy and his friends asks Eurytion about how he got the metal spider, Eurytion replied that a couple of years back he helped Hephaestus play a little practical joke on his father Ares, and Hephaestus gave him the spider in appreciation so that Eurytion can visit him whenever he wished (but only once). It is possible, though unconfirmed, that the practical joke was the same one Hephaestus tried to pull on Ares in The Lightning Thief, seeing as it involved mechanical spiders.
- In The Last Olympian, when Percy chooses to stay mortal, he does not think about Eurytion although Eurytion chose immortality.