While in exile, Thyestes learned from the Delphic oracle that to avenge himself he had to have a son by his own daughter, Pelopia. One night he disguised himself and slept with his daughter, who did not know his true identity. Another version of the story tells that Thyestes raped a priestess whom he spied bathing in Sicyon after she had conducted nocturnal rites to Athena. Unknown to him, the priestess was actually Pelopia, and he left without either father or daughter realizing the other’s identity.
Meanwhile, Atreus had killed Aerope for her infidelity, but not before she had given birth to his sons Agamemnon and Menelaus. Soon afterward, on a visit to Sicyon, Atreus
Fell in love with and married Pelopia, whom he assumed was a Sicyon princess, the daughter of King Thesprotus. Several months later Pelopia gave birth to a son, Aegisthus; unknown to Atreus, the infant was Thyestes’ son, not his.
Years later Atreus sent Aegisthus on a mission to assassinate Thyestes, whom Atreus had captured and imprisoned in Mycenae. As Aegisthus approached, Thyestes recognized the sword the young man was carrying as his own. At the time of the rape, Pelopia had stolen Thyestes’ sword from its scabbard and had later given it to Aegisthus. Instead of killing Thyestes, Aegisthus murdered Atreus and made his real father king of Mycenae.
In a different version of the story, another one of Atreus’s sons was Pleisthenes, who was sometimes spoken of as the father of Agamemnon and Menelaus, making them actually the grandsons of Atreus. When Thyestes went into exile after his attempt to acquire the throne of Mycenae, he took Pleisthenes with him, pretending that he was his own son, not the son of Atreus, who was also ignorant of his paternity. Later Thyestes sent Pleisthenes back to Mycenae with instructions to kill Atreus, which induced Atreus to have Pleisthenes killed, thus unwittingly murdering his own son.
World History
