In mythology we don't frequently see doublets. Most gods, goddesses, or characters of note are unique unto themselves. Odysseus was nothing like Hercules, Zeus was nothing like Poseidon, and Athena was nothing like Aphrodite. To the best of my memory all the stories of these individual characters in Greek mythology are unique unto themselves. Atlas hold ups the globe, no one else has that job. Hercules goes on twelve labors, no one else does that. When we come to Europa and Pasiphae however, we see too much similarity to ignore.
Europa was the sister of Cadmus a Phoenician and both the founder and the King of Thebes. A Phoenician herself, Europa was a Princess, the daughter of Agenor - the King of Tyre. "The Seduction of Europa", commonly called "the Abduction of Europa", and somewhat less tastefully "The Rape of Europa", tells about Zeus's seduction of the Princess. The story goes like this:
Zeus observes Europa picking flowers in a field and falls immediately in love with her. He concocts a plan to seduce her in the classic Greek way - meaning overly convoluted and involving transfiguration - by turning into a magnificent white bull. The bull approaches Europa and kneels at her feet. Europa is so impressed by the bulls beauty and gentle movements that she adorns its neck in flowers and climbs atop the beast.
At this moment the bull runs off into the sea, escaping them both to the Island of Crete. Once on Crete, Zeus reveals his true form and makes love to Europa. She becomes the Queen of Crete.
Pasiphae was the immortal daughter of the sun-god Helios and sister to Aeetes and Kirke; she was, and this is not controversial, a witch. That is to say, she possessed the power of Pharmakeia. She wed King Minos, son of Europa and Zeus, and became the Queen of Crete. Timelines are a bit confusing here but before King Minos ascended to the throne of Crete he asked Poseidon for a sign of his success (re: if I try to become King, will I become King?). Poseidon answered by sending a white bull out of the sea. Minos was so struck by the magnificence of this white bull that he made a foolish decision.
Instead of sacrificing this bull to Poseidon in thanks for his help, he swapped it out for another white bull that wasn't near as magnificent. This infuriated Poseidon and, as is often the case in Greek lore, he decided to take his anger out not on Minos, but on his wife. Poseidon cursed Pasiphae with lust for the white bull that Minos so coveted.
Things get really weird here. Pasiphae has such strong sexual feeling for this bull that she enlists Daedalus, the brilliant inventor, to build her a wooden cow to conceal her. The idea being of course that Pasiphae would "present" herself to the bull disguised as a cow and that the bull would mount and mate with her.
That is exactly what happened.
The result of this strange union was the Minotaur of legend; the Minotaur of Daedalus' Labyrinth.
The most obvious: the white bull emerging from the sea. This is some very specific symbolism, and to see it twice, on the same island, in the same family, is strange.
Next: the absence of full control by the women involved in concerns to the intercourse featured in both stories. Europa wasn't raped so much as she was kidnapped. Her intercourse with Zeus, once he revealed his true form, was desired by both parties. Pasiphae, on the other hand, was worse than raped. Pasiphae had her mind manipulated to desire intercourse with a beast. Imagine waking up out of that trance and remembering that, for some unexplained reason, you wanted to hide in a wooden cow so that a bull would have sex with you. Poseidon is far and away the bigger monster in these two stories; and Pasiphae the bigger victim; a puppet in an awful revenge plot.
Lastly: And this isn't a common theme so much as it's interesting to consider: These women knew each other. Europa was Pasiphae's mother-in-law. They lived in the same house, never discussed Europa's experience and yet both ended up lusting for a white bull. I often wonder if there's some missing part of the story, some irony intended on the part of Poseidon by choosing a white bull from the sea to deliver his revenge.
Something more to think about
Pasiphae, after this whole thing was over, discovered her husband was unfaithful on a regular basis. She, being a witch, cursed him - but it is how she cursed him that is so devilishly worthwhile.
Pasiphae cursed Minos so that when he ejaculated, he ejaculated poison creatures into his lovers. Those lovers would immediately die. In this way she forced Minos, if he wanted to have sex, to only have intercourse with her as she was immune.
And that last bit makes this story extra interesting to think about: One could easily say that each character here was a victim of rape. Europa gave into Zeus because he was an attractive and powerful God. Pasiphae gave into a beast because she had been cursed. Minos gave into his wife because he had no choice.
All of that sparks thoughts worthy of group discussion in a college level philosophy class!