In the Warner Bros. movie "Troy," Briseis plays the love interest of Achilles. Briseis is portrayed as a war prize given to Achilles, taken by Agamemnon, and returned to Achilles. Briseis is a virgin priestess of Apollo. The legends say slightly different things about Briseis.
In the legends, Briseis was the wife of King Mynes of Lyrnessus, an ally of Troy. Achilles slew Mynes and the brothers of Briseis (children of Briseus), then received her as his war prize. Even though she was a war prize, Achilles and Briseis fell in love with each other, and Achilles may have gone to Troy intending to spend much time in his tent with her, as was portrayed in the movie. But then Agamemnon took Briseis from Achilles. Agamemnon did this not merely to make an arbitrary statement about his superior power-as shown in the movie, but because he had been obliged to return his own war prize, Chryseis, to her father. Chryses, the father of Chryseis, was a priest of Apollo. In the movie, Briseis is a priestess of Apollo. After Chryses learned of his daughter's abduction, he tried to ransom her. Agamemnon refused. The gods responded… The seer Calchas told Agamemnon that the Greeks were suffering from a plague sent by Apollo because he wouldn't return Chryseis to Chryses. When, reluctantly, Agamemnon agreed to return his prize, he decided he needed another one to replace his loss, so he took Achilles' and said to Achilles:
" Go home, then, with your ships and comrades to lord it over the Myrmidons. I care neither for you nor for your anger; and thus will I do: since Phoebus Apollo is taking Chryseis from me, I shall send her with my ship and my followers, but I shall come to your tent and take your own prize Briseis, that you may learn how much stronger I am than you are, and that another may fear to set himself up as equal or comparable with me."
Iliad Book I
Achilles was enraged and refused to fight for Agamemnon. He wouldn't fight even after Agamemnon had returned Briseis-untouched (as was shown in the movie). But when Achilles' friend Patroclus died, killed by Hector, Achilles went mad and determined to get revenge, which meant going to war.
Briseis and Achilles may have intended to marry.