As in, ‘What is Achilles’ motivation?’

Achilles’ fate is to die at Troy, and once Agamemnon has removed kudos from him in Book 1 of the Iliad by disrespecting him and taking his prize (the slave Briseis), doing so in front of the other heroes, Achilles ostensibly removes himself from the fighting until this slight is righted.

Read more about Aidos at https://en.wikipedia.org/wiki/Aidos

Read more about Kleos (Kudos) at https://en.wikipedia.org/wiki/Kleos