Atreus and Thyestes were brothers, the sons of Pelops and Hippodameia. They grew up together and played together. But instead of loving each other, they were always rivals in everything. This may have been partly because of the curses on Tantalus, their grandfather, and Pelops, their father.

When they grew up, Atreus married the daughter of the King of Mycenae, and so he soon became the King of Mycenae himself. But Thyestes was jealous.

One day, Atreus promised to sacrifice the best lamb in his flock to the goddess Artemis. Later that afternoon, as he went walking among his sheep, Atreus found a lamb with a golden fleece! Certainly he should have sacrificed that one to Artemis, but he didn't want to sacrifice such a beautiful thing, so he killed the lamb and kept the golden lambskin in a box instead.

The entrance to the palace at Mycenae

But Atreus' wife, the Queen, was secretly in love with Thyestes. She agreed to steal the golden lambskin and give it to Thyestes. Then Thyestes dared Atreus to make a deal with him. He said, "Let's say whoever has the golden sheepskin can be King of Mycenae." Well Atreus knew that he had it in his box, so he agreed. But then it turned out that Thyestes had it, so he got to be King. Atreus was very angry.

Atreus went to Zeus (his great-grandfather through Tantalos) and complained. Zeus told Atreus to make a bet with Tantalos that if the sun ran backward, Atreus could be king again. Tantalos thought, "Nobody can make the sun run backward!" so he agreed. But the gods can do anything, so Zeus did make the sun run backwards. Atreus got to be King of Mycenae again, and he banished Thyestes from the kingdom.

But Atreus couldn't let it go at that. He was still very angry at his wife and Thyestes. So he pretended to be friendly and invited Thyestes to come over for dinner, with his two little boys. Thyestes was happy that he was going to be reunited with his brother! When Thyestes arrived,  Atreus sent the boys out to play and sat down for a good talk with Thyestes. Soon the slaves brought dinner in, and they ate course after course of delicious food. Then another slave brought in the dessert in a big covered dish.

But when the slave took the cover off the dish, Thyestes was horrified to see his two sons’ bloody heads and hands and feet! Atreus had murdered them and cooked them and served them to him for dinner. Thyestes just ran out of the palace and never came back again. He did, however, have one more son, Aegisthus, who eventually avenged him.