Helen of Troy refuge with Leda. The swan gained her affection, and the two mated. Leda then produced an egg, from which Helen emerged. The First Vatican Mythographer introduces the notion that two eggs came from the union: one containing Castor and Pollux; one with Helen and Clytemnestra. Nevertheless, the same author earlier states that Helen, Castor and Pollux were produced from a single egg. Pseudo-Apollodorus states that Leda had intercourse with both Zeus and Tyndareus the night she conceived Helen. On the other hand, in the "Cypria", part of the Epic Cycle, Helen was the daughter of Zeus and the goddess Nemesis.
Amphion and Zethus Amphion and Zethus Amphion () and Zethus (, "Zēthos") were, in ancient Greek mythology, the twin sons of Zeus (or Theobus) by Antiope. They are important characters in one of the two founding myths of the city of Thebes, because they constructed the city's walls. Amphion and Zethus were the sons of Antiope, who fled in shame to Sicyon after Zeus raped her, and married King Epopeus there. However, either Nycteus or Lycus attacked Sicyon in order to carry her back to Thebes and punish her. On the way back, she gave birth to the twins and was forced to