Zeus had received a prophecy that Thetis's son would become greater than his father, like Zeus had dethroned his father to lead the succeeding pantheon.
'This is a sorry business, indeed, and you will force a quarrel with Hera. She will taunt and rile me. As it is, she scolds me endlessly before the other gods, claiming I aid the Trojans in battle. Go now, before she notices, while I think the matter through. Come, I will nod my head, to reassure you, since you immortals know this as my sure pledge; once I give the nod, my word can never be recalled, it proves true and is fulfilled.' - Zeus, the Illiad, granting the request of Thetis to honor her son Achilles; and explaining that in doing so he earns the ire of his sister and wife Hera.
Thetis’ second child was Achilles, a legendary Greek hero who played a major role in the Trojan War.
Cassiepeia the wife of Cepheus in Acthiopia, and mother of Andromeda, whose beauty she extolled above that of the Nereids. This pride became the cause of her misfortunes, for Poseidon (whose wife Amphitrite was a Nereid) sent a monster into the country which ravaged the land, and to which Andromeda was to be sacrificed. But Perseus saved her life. According to other accounts Cassiepeia boasted that she herself surpassed the Nereids in beauty, and for this reason she was represented, when placed among the stars, as turning backwards.
Hermes is the son of Zeus and a member of the 12 Olympian gods in Greek mythology. He is known as the messenger of the gods and is often portrayed as a clever and mischievous figure who carries out tasks for Zeus. Zeus trusted Hermes and relied on him for delivering messages and running errands.
Zeus generally has a favorable attitude toward Odysseus in Homer's epic poems. Zeus sometimes intervenes on Odysseus' behalf, such as by sending Hermes to help him or by ensuring he eventually returns home to Ithaca. Zeus respects Odysseus for his cunning and resourcefulness, which align with Zeus' own qualities.
Athena was a child by METIS and Zeus. not thetis.
Because Achilles is the child of Thetis and Zeus, and he owed her one.
No, Thetis was the daughter of Doris and Nereus.
Thetis does not promise anything, but Zeus does promise Thetis that her son Achilles will be honored.
Zeus, whose throne Thetis had protected by summoning the giant Briareus when the gods had sought to bind him.
Both Zeus and Poseidon wanted to marry Thetis but as they were 2 of the big three of Olympus they weren't allowed to openly do battle. (The universe may have fallen apart if they did) So they went to arbitration with Prometheus as the arbitrator. And Prometheus had a prophesy that 'the first child of Thetis will overthrow his father'. Now overthrowing ones father was a sad tradition in the Titan family. Zeus and Poseidon (along with Hades) had overthrown their father Chronos, and he had overthrown his father Uranus. Zeus had already foiled one such attempt around the Goddess Minerva (her child however turned to be a girl (Athena) and fortunately those things don't count for anything.) So both Zeus and Poseidon didn't want to have anything to do with her anymore and they gave her to Peleus. The first child of Peleus and Thetis was Achilles.
She promises to ask Zeus to side with the Trojans in the battle.
Thetis was promised that Achilles would have honor and glory.
To shjow why Zeus a powerful god would make a promise and help the Nereid Thetis.
Hera made Zeus give Thetis to a mortal man as his wife.
No, Achilles is the son of Peleus and Thetis.
Zeus had received a prophecy that Thetis's son would become greater than his father, like Zeus had dethroned his father to lead the succeeding pantheon. In order to ensure a mortal father for her eventual offspring, Zeus and his brother Poseidon made arrangements for her to marry a human, Peleus, son of Aeacus, but she refused him. Proteus, an early sea-god, advised Peleus to find the sea nymph when she was asleep and bind her tightly to keep her from escaping by changing forms. She did shift shapes, becoming flame, water, a raging lioness, and a serpent. Peleus held fast. Subdued, she then consented to marry him. Thetis is the mother of Achilles by Peleus, who became king of the Myrmidons.