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.
Helen of Troy brought no gifts because he believed he had little chance to win the contest. He thus promised to solve the problem, if Tyndareus in turn would support him in his courting of Penelope, the daughter of Icarius. Tyndareus readily agreed, and Odysseus proposed that, before the decision was made, all the suitors should swear a most solemn oath to defend the chosen husband against whoever should quarrel with him. After the suitors had sworn not to retaliate, Menelaus was chosen to be Helen's husband. As a sign of the importance of the pact, Tyndareus sacrificed a horse. Helen and Menelaus