Poseidon raped Demeter
The Greek geographer Pausanias explains the myth of Demeter's rape by Poseidon in his account of Greece. He claimed that while Demeter was traveling the earth in quest of her daughter, Persephone, Poseidon sexually assaulted her.
When Poseidon first saw Demeter, he was captivated by her beauty. Demeter learned about it and posed as a mare to flee from the man. She was raped by Poseidon, who had disguised himself as a stallion, so she was unable to flee.
Areion, an eternal horse, was said to have been born of Demeter. Another child of Demeter and Poseidon was named Despoina. She was revered alongside her mother Demeter as the goddess of secrets in Arcadian religions.