Thetis, like all the 50 Nereids, was a daughter of the old sea god Nereus and the sea goddess Doris. Zeus had courted Thetis, who had once helped rescue him from a rebellion by Poseidon, Hera, and Athena (see Chapter 6). But the ruler of the gods lost interest in the sea nymph when he learned from Prometheus that the son she would bear would become greater than his father. Remembering that he had overthrown his own father to become king of the gods and fearful of suffering the same fate himself, Zeus decided that Thetis should not marry any god. Instead, she would become the rare goddess who married a mortal. Zeus chose Peleus, who had inherited the throne of Phthia from his father-in-law Eurytion. (Antigone, Peleus's first wife, had killed herself when Astydameia's lies raised doubt about her husband's fidelity.)
Cheiron, immortal king of the Centaurs, soon sent his friend Peleus to Thetis's favorite grotto. Cheiron told Peleus that if he could hold on to the sea goddess through all her transformations, she would become his bride. Peleus found 'Thetis, wrapped his arms around her, and refused to let go. Though she changed into fire, water, a lioness, a snake, and a cuttlefish, Peleus held on tight. Finally, the sea goddess yielded, consenting to be his wife.
All the gods and goddesses attended this legendary wedding. The gods, already honoring the couple with their presence, added to the honor with presents. 'Thetis received a magnificent jeweled crown from Aphrodite. To Peleus, the gods brought two immortal horses, Xanthus and Balius.
Unfortunately, the only goddess not invited to the wedding tried to crash the party. When she was still refused admittance, she used the Golden Apple--and the rivalry it sparked among three goddesses--to sow the discord that would lead to the 10-year Trojan War.
Thetis--a minor goddess perhaps, but still a goddess--was not content to have a mere mortal as a son. So when her child, Achilles, was born, she set about to make him an immortal. Heracles, you'll recall, burned off his mortality on a funeral pyre, while the immortal part of him ascended to Mount Olympus. Thetis hoped to do the same for her son. So she anointed him with ambrosia by day and set him on the coals at night. Peleus saw his son on the coals one night and quickly pulled him off. Thetis, insulted by her husband's lack of faith in her, abandoned both Peleus and her son and returned to the sea.
Mythmakers do not agree on just how Thetis made her son immortal. Some say the goddess dipped the baby in the river Styx, which burned the mortal life away from him and made him nearly immortal--except for the heel by which Thetis held him. Others insist that Thetis had already given birth to several children before Achilles was born. To test their mortality, she dipped each child into a pot of boiling water, but none had survived the test. When Peleus saw his wife trying this test with Achilles, he pulled his child from the pot not even realizing that the boy had passed the test--again except for the heel by which Thetis held him.
Thetis, however, knew that her son was fated to die if he fought in the Trojan War. So in an attempt to keep him from joining Menelaus in the campaign to recover Helen, the goddess disguised Achilles as a girl and sent him to the Aegean island of Scyrus. Called by the feminine name of Pyrrha, Achilles lived among the daughters of King Lycomedes (yes, the same Lycomedes who killed Theseus).
Placing a handsome and virile teenage boy--even one disguised as a girl--in the same bedroom as several pretty teenage girls had predictable results. Shortly after Achilles left the island, Deidameia, one of Lycomedes's daughters, gave birth to a son. She named the boy Pyrrhus, in honor of the "girl" who fathered him. (After Achilles's death, Phoenix renamed the boy--who would contribute greatly to the Greek victory--Neoptolemus, meaning New War.)
When Odysseus came to Scyrus to enlist Achilles for the war effort, Lycomedes claimed that the boy was not there. But the wily Odysseus knew a lie when he heard one, and he devised a scheme to get Achilles to reveal himself.
Odysseus laid a spear and a shield down on the porch next to a handful of baubles and trinkets. He invited all the "king's daughters" to play with the pretty jewels. But while the girls played, the ship's trumpeter--acting under Odysseus's orders--sounded a martial call, indicating that they were under attack. The trick worked. As soon as the horn blew, Achilles alone dropped the baubles, seized the sword and shield, and stripped off his feminine clothes. Gotcha!