Eurytion

Eurytion is the son of Ares and Erytheia.

History
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. Immortality meant thousands of years serving Geryon and killing anyone he wanted to kill.

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 Heracles 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 wasn't immortal, he was a monster.

The Battle of the Labyrinth
In The Battle of the Labyrinth, Eurytion finds Percy, Annabeth, Grover, and Tyson coming out of the Labyrinth. He takes them to Geryon, and is kind to Annabeth.

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.

Personality
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.

Appearance
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. Percy decribes him as a kind of "Father Time" gone redneck and totally jacked.

Powers

 * 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.

Trivia

 * When Percy and his friends asks Eurytion about how'd he get 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 that this 'practical' joke could be the one that happened in The Lightning Thief in the Waterland park (in which Hephaestus tried to catch Ares and Aphrodite on a Tunnel of Love ride).
 * In The Last Olympian, when Percy chooses to stay mortal, he does not think about Eurytion although Eurytion chose immortality.