Thetis gives him his new armor, and promises, after hearing Achilles' concerns for the body, that she will keep the body as fresh and whole as it was when Patroclus was alive.
Thetis does not promise anything, but Zeus does promise Thetis that her son Achilles will be honored.
She promises to ask Zeus to side with the Trojans in the battle.
Achilles.
Achilles
No, Achilles is the son of Peleus and Thetis.
Thetis largely helped her son Achilles achive his wish of glory.
To shjow why Zeus a powerful god would make a promise and help the Nereid Thetis.
That she will one day bear a son more famous than his own father.
Peleus, son of Aeacus.
Thetis gives him his new armor, and promises, after hearing Achilles' concerns for the body, that she will keep the body as fresh and whole as it was when Patroclus was alive.
Thetis gave prophesy that she would have a son greater than his father; Zeus and Poseidon did not pursue her afterwards but made it so she would have a son by a mortal. That son was Achilles.
Thetis tried to conceal him by hiding him disguised as a girl in the court of Lycomedes.