Argus was created by Hera and acted as her servant. His great service to the Olympians was to slay Echidna, the mother of monsters, as she slept in her cave. Hera's personal task for Argus was to guard the white heifer, Io, a mistress of Zeus, from him. He kept her chained to the sacred olive tree at Argive Heraion until Hermes (in some versions Pan or Apollo) sang or talked to him until he was drowsy and then touched all of his eyes, putting him in a deep sleep which allowed the god to free Io.
After Percy Jackson's battle with the Minotaur, he wakes up every now and then in the Big House. One time, he woke and saw Argus with eyes all over his body before losing consciousness again. Argus drives Percy, Annabeth Chase and Grover Underwood out of Camp Half-Blood to start their quest. At the end of the book, Argus helps Percy to his cabin to pack his things.
When Percy first arrives at camp, he finds out that both Chiron and Argus have been fired. When Percy gets Luke Castellan to reveal to the camp that Chiron was innocent, it can be presumed that he was hired again along with Chiron.
Late at night at Camp Half-Blood, Zoë Nightshade has a dream about Artemis, the Olympian goddess of the moon and the hunt, and demands to speak to Chiron, but Argus refused to allow her into the Big House. From what Grover told Percy, Zoë and Argus got into a verbal argument, including Zoë calling Argus a "boil-brained lout," until Chiron came. When Percy follows Thalia Grace, Grover, Zoë and Bianca di Angelo, Blackjack informs him that Argus was not driving the Camp Half-Blood van, but that Zoë was.
Argus drives the demigods out of Camp Half-Blood to meet Percy at the rendezvous spot in front of the Empire State Building in Manhattan, NYC before the Battle of Manhattan and goes back to defend camp. He also passes Annabeth a video shield made by Beckendorf before he died that can show anywhere you wish to see as long as there is natural light reflecting off it. After Percy hears Rachel Elizabeth Dare took his Pegasus Blackjack to camp, Percy, Annabeth and Nico di Angelo go after her. Argus came to greet them and they witnessed Rachel becoming the new Oracle of Delphi for Camp Half-Blood.
Piper McLean loses consciousness after Hera speaks through the oracle, Rachel, to Piper and is taken to the camp's Big House. When she wakes up, she sees Rachel and Argus there. Argus is unhappy by Hera's disappearance and Rachel says that Hera created Argus and he is protective of her. He starts to cry, which Rachel says they try to keep him from doing since he nearly flooded the camp the last time.
Argus looks embarrassed that the Maenads got in Camp Half-Blood without him knowing it.
Not much is known about Argus' personality as he doesn't usually talk. He is shown to be a man of rules, since he wouldn't let Zoë in to see Chiron in The Titan's Curse. Argus is very protective of his creator Hera, being very protective and emotional about her. He is also annoyed when he discovered that the gods wouldn't be 'riding to the rescue' in The Last Olympian, since he rolled his eyes when Percy told him.
Percy Jackson describes Argus to look like a "typical blond surfer dude", with the exception that he has a hundred blue eyes all over his body and supposedly has one on his tongue. The latter is the main reason why he doesn't talk much. When he rolls his eyes, it looks like his body is swirling.
- As a giant, Argus possesses great physical stature and strength.
- When Argus cries, it causes floods.
- He is a great driver, even in the middle of battle.
- Argus is the name of the man who built the Argo for Jason and the Argonauts.
- Argus is one of the few supporting characters that made an appearance in all books, until The Son of Neptune.
- It's unknown how he ended up at Camp Half-Blood, or whether it was of his own free will or if a god wanted him to do it.