Once upon a time, King Atreus of Mycenae, after learning about the infidelity of his wife Aerope, who was the mistress of his brother Thyestes, called Thyestes back from banishment, with the secret desire of punishing him.
Atreus prepared a dinner, similar to the dinner prepared long ago, by his grandfather Tantalus. Atreus slaughtered the sons of Thyestes into pieces. He boiled, cooked and offered the pieces as a delectable special meal, to Thyestes. The unaware Thyestes, consumed the flesh of his own sons. When the cannibalistic banquet ended, Atreus showed to Thyestes, the chopped off hands and feet of the slain sons. After gaining the pleasure of witnessing the torment of Thyestes, Atreus again banished Thyestes.
The utterly dejected Thyestes, consulted the Delphian oracle, seeking how he might obtain vengeance on his brother Atreus. The oracle told Thyestes to impregnate his own daughter Pelopia, and produce a son, who shall avenge him. Hearing the oracle, the shocked Thyestes left Delphi and proceeded in his rootless roaming.
While wandering, Thyestes arrived at Sicyon, where some maidens were dancing at night, in a sacrifice at the temple of Athena. Not wishing to spoil the sacred rites, Thyestes moved away towards a stream and hid behind a tree. Leading the dancing maidens was the virgin Pelopia, who accidentally slipped and her dress got stained, by the blood of the slain sacrificial animal. To wash off the stain, Pelopia came to the stream, but suddenly Thyestes came out from behind the tree and raped his own daughter. While Thyestes stole the virginity of Pelopia, Pelopia was able to steal the sword of Thyestes. Pelopia managed to draw the sword from its sheath, but before she could attack, Thyestes fled away, unrecognized in the darkness.
Pelopia returned to the temple and hid the sword, beneath the statue of Athena. Unaware that the seed was of her own father, Pelopia conceived Aegisthus in her womb.
Excerpt from the book “Once Upon A Time-II: 150 Greek Mythology Stories” by Rajen Jani