Upon the death of the king his father, Pandion II, Aegeus and his three brothers, Pallas, Nisos, and Lykos, took control of Athens from Metion, who had seized the throne from Pandion. They divided the government in four but Aegeas became king. His first wife was Meta and the second was Chalciope.
Still without a male heir, Aegeus asked the Oracle at Delphi for advice. Her cryptic words were "Do not loosen the bulging mouth of the wineskin until you have reached the height of Athens, lest you die of grief. Ignoring the oracle, Aegeus returned home by way of Troezen, where he was induced to father Theseus, perhaps drunkenly, and thus eventually did die of grief (see below).
Aegeus went to Troezen where he was the guest of Troezen's king Pittheus. Pittheus understood the prophecy and introduced Aegeas to his daughter, Aithra, when he was drunk. They slept with each other and then, in some versions, Aethra waded out to the sea to the island of Sphairia, and bedded also with Poseidon. When she fell pregnant, Aegeus decided to go back to Athens. Before leaving, he covered his sandals, shield and sword under a huge rock and told her that when their son grew up, he should move the rock and bring the weapons back, by which sign his father would acknowledge him. Upon his return to Athens, Aegeus married Medea who had fled from Corinth and the wrath of Jason. Aegeus and Medea had one son together named Medus.
In Troezen, Theseus grew up and became a brave young man. He managed to move the rock and took his father's arms. His mother then told him the identity of his father and that he should take the weapons back to him at Athens and be acknowledged. Theseus decided to go to Athens and had the choice of going by sea, which was the safe way or by land, following a dangerous path with thieves and bandits all the way. Young, brave and ambitious, Theseus decided to go to Athens by land.
When Theseus arrived, he did not reveal his true identity. He was welcomed by Aegeas, who was suspicious about the stranger who came to Athens. Medea tried to have Theseus killed by encouraging Aegeas to ask him to capture the Marathonian Bull, but Theseus succeeded. She tried to poison him, but at the last second, Aegeas recognized his sword and knocked the poisoned cup out of Theseus' hand. Father and son were thus reunited, and Medea sent away.
Aegeus had told Theseus, before he left, to put up the white sails when he left Crete, if he had been successful in killing the Minotaur. Theseus forgot, and Aegeus jumped into the sea when he saw the black sails coming into Athens, in the mistaken belief that his son had been slain, thus fulfilling the prophecy. Henceforth, this sea was known as the Aegean Sea.
At Athens, the traveller Pausanias was informed in the second-century CE that the cult of Aphrodite Urania above the Kerameikos was so ancient that it had been established by Aegeas, whose sisters were barren, and he still childless himself.