Once upon a time, Zeus burned for the love of Nemesis, the messenger of Justice, also known as Divine Retribution, or the decree establisher for the transmission of the soul from one body to another. Nemesis fled from the advances of Zeus, by changing her form to a fish and several other creatures. But when Nemesis took on the shape of a goose, Zeus promptly changed his shape to a swan, and consorted with her. As a result, she laid an extraordinary egg. A shepherd found the beautiful egg and gave it to Leda, the wife of King Tyndareus of Sparta. In due time, Helen, the daughter of Zeus and Nemesis, was hatched from this egg. Leda brought up Helen as her own daughter. Helen grew up to be an astoundingly beautiful girl, whose beauty was famed far and wide.
Meanwhile, Phaedra the wife of King Theseus of Athens had died and Hippodamia, the wife of Pirithous had also died. Theseus and Pirithous were friends and they decided to abduct Helen, who was twelve years old. When Helen was sacrificing in a temple of Artemis, they carried her off. Then they cast lots for Helen and Theseus won. Theseus secretly took Helen to Aphidnae, a city in Attica.
The two brothers of Helen, Castor and Polydeuces, also known as the Dioscuri, came to Athens with a large army to rescue their sister. The Dioscuri waged war and captured Athens. They made Menestheus, a member of the royal house of Athens, as the king of Athens. At that time, an Athenian named Academus, who had somehow come to know that Theseus had taken Helen to Aphidnae, revealed it to the Dioscuri.
The Dioscuri conquered Aphidnae, rescued Helen and took Aethra the mother of Theseus, to serve as a slave to Helen. Theseus was exiled and while still in exile, he died on the isle of Scyros. Helen, desiring to be known as a virgin, entrusted her daughter Iphigenia, whom she bore to Theseus, to the care of her sister Clytaemnestra.
Excerpt from the book “Once Upon A Time-II: 150 Greek Mythology Stories” by Rajen Jani