As the story goes .....
Venus was probably Jupiter's daughter. So was Helen. But Helen's mother was only a mortal. Venus's mother was probably a goddess. Although that made the girls half sisters, probably, to Venus, there was no comparison. Venus was the goddess of love. Helen was .. Helen, the Queen of Sparta, and quite stuck up about it, too.
When Venus heard that Paris, a prince of Troy, had proclaimed her half sister Helen as the fairest in the land, Venus was not at all pleased.
"Everyone knows that I'm the fairest," mumbled Venus, quite put out about it.
A short time later, a wedding was announced in the Roman god world. Discordia, the spirit of disagreement, had not been invited. Discordia made a surprise and most unwelcome visit to the wedding reception. She threw a golden apple of discord on the feasting table. "This apple is for whomever is the fairest," Discordia proclaimed haughtily, hoping to cause trouble.
Juno, Venus, and Minerva all grabbed for the apple. "It's mine," insisted the three goddesses, Venus loudest of all.
Jupiter thundered, "Enough. Paris will decide who is the fairest. Mercury, go tell Paris he has a job to do."
"Paris!" Venus muttered. "Well, well."
Venus made sure her bribe was the best. She promised Paris that Helen, Queen of Sparta, would fall in love with him. She promised his brothers would be jealous! No one knows if it was the thought of the beautiful Helen or the thought of his brothers' jealously, but Paris took the deal. Venus kept her promise. That very day Paris and Helen traveled together to the city of Troy, where they expected to live happily ever after.
When the king heard his wife had been kidnapped, he called on the other city-states in ancient Greece to help him rescue her. A huge body of fighting men set out for Troy. That was the end of Troy, and of Paris. As for what happened to Helen, Venus never asked.