This here is a visual outline of the hero's journey of Achilles.
The Ordinary World
Call to Adventure
Refusal of the Call
Achilles was the son of the sea-goddess Thetis and mortal hero, Peleus. He lived peacefully with his mother.
Meeting the Mentor
The Trojan War (Greek vs. Trojans) arises and Achilles couldn't help but want to butt in.
Crossing the Threshold
Thetis feared that Achilles was going to die in war so she disguised him like a 15-year-old girl, gave him a female name, and hid him in the palace of a king she knew.
Tests, Allies, and Enemies
The prophet Calchas, who was given the ability to whom Apollo gave the knowledge of the past and future, explains to Achilles that the only way to remove the plague that has been placed (because Agamemnon dishonored the priest by not returning the priest's daughter) is to return the daughter with no gifts in return.
The Greek army then makes their way to Troy and reach the Simois Trojan river.
Agamemnon is advised to apologize to Achilles and offers Achilles many gifts to join the war again and keep Hector from burning their ships. Achilles, however, refuses.