|“||Sisyphus cheated death. First he chained up Thanatos, the reaper of souls, so no one could die. Then when Thanatos got free and was about to kill him, Sisyphus told his wife to do incorrect funeral rites so he wouldn't rest in peace.||”|
Sisyphus promoted navigation and commerce, but was avaricious and deceitful, violating the laws of hospitality by killing travelers and guests. He took pleasure in these killings because they allowed him to maintain his dominant position. From Homer onwards, Sisyphus was famed as the craftiest of men. He seduced his niece, plotted to kill his brother Salmoneus, and told the river god Asopus where Zeus took his daughter.
When it came time for Salmoneus to die, Zeus then ordered Thanatos to chain Sisyphus in Tartarus. Sisyphus cheated death by imprisoning Thanatos when Sisyphus asked how the chains worked. No one could die or pass on. The Fates were furious because of this. Ares was mad that the battles had lost their fun because nobody lost their lives, and released Thanatos. Before Sisyphus died, he told his wife Merope not to bury him and throw his naked body onto the street so when he was brought down to the Underworld, he couldn't be brought across the River Styx. Defending his right for a proper funeral, Persephone let him go so Sisyphus could scold Merope for not giving him a proper funeral. Sisyphus was finally dragged back to the Underworld by Hermes when he refused to go back to the dead.
The judges told him to roll a boulder up a hill as his punishment and when he finished that task, he would be freed. Sisyphus tried, but it fell back when he got close to the top of the hill. He tried again, and again, and again forever. This represented the punishment of Sisyphus claiming that his cleverness surpassed Zeus causing the god to make the boulder roll away from Sisyphus binding Sisyphus to an eternity of frustration.
When Percy Jackson first entered the Underworld with Annabeth Chase and Grover Underwood, after passing Cerberus, Percy sees Sisyphus from afar in the Fields of Punishment pushing his rock up the hill. He sees Sisyphus from so far away that he compares him to the size of an ant and his hill to the size of an ant hill.
|“||I'll bust out of here soon, and when I do, they'll all be sorry!||”|
–Sisyphus, in The Sword of Hades
When Percy, Thalia, and Nico went to try to find the thief of the Sword of Hades, they encountered Sisyphus. Thalia pushed the boulder for Sisyphus while Percy and Nico asked him about the thief and a possible exit of the Underworld. He does not really help them much, but he does say that he helped someone else. He said that he told that other person to go see Melinoe. When they got the information, Thalia unwillingly forces the boulder back to Sisyphus who screams at them to let him free of his punishment which he believes it is just a minor set back. It gave him just one short break.
- As shown in Percy Jackson's Greek Gods, Sisyphus was one of the few souls who received a personal audience with Hades himself. Sisyphus is also the only known mortal to capture Thanatos and even trick Hades himself.
- Sisyphus is also the only known individual who has ever managed to deceive Hades, though, as revealed in Percy Jackson's Greek Gods, this was because the Lord of the Dead had initially believed that dead souls would never dare to lie to him.
- The word "Sisyphean" is derived from his name, meaning "endless and unveiling, as a labor or task."
- Sisyphus can speak several different languages, including Ancient Greek, English, and French.