Pirithous had heard of Theseus' courage and might, so he wanted to see it with his own eyes. He stole Theseus' cattle, and Theseus went out to find him. The two met fully armoured and were so impressed with each other that they became close friends. Both Pirithous and Theseus took part in the hunt for the Calydonian Boar. Pirithous then met and married Hippodamia; during the wedding, the Centaurs got drunk and tried to abduct the women. A battle followed between the Centaurs and the Lapiths, which was named Centauromachy, and resulted in the victory of the latter.
The two friends decided to kidnap two daughters of Zeus; Theseus kidnapped Helen of Sparta, who being thirteen years old, was then given to Theseus' mother Aethra. Pirithous instead took a higher risk and decided to kidnap Persephone, wife of Hades. While in the Underworld, the two men sat on a rock to rest and realised they were unable to stand when they saw the Furies come for them. Heracles managed to free Theseus, but when he tried to liberate Pirithous, the earth started shaking; Pirithous had committed a grand hubris for trying to kidnap a god's wife.