Mafia 19. Trojan War.

Cassandra is the daughter of Priam and Hecuba. A prophetess, and the most beautiful of Priam's daughters.

in the movie, she had an affair with Achilles, or

Briseis is the daughter of Bris, a priestess of Apollo, who became Achilles' concubine.

the idea is that she was the sister of Hecamede and Paris, but at the same time, she was also a priestess of Apollo, which is why I got confused.