Sentence:  The character of <WSD>Briseis</WSD> and the story of her relationship with Achilles stand in the background of the entire "Iliad": the poem opens, literally, with Achilles' anger, which at 1.298–9 turns out to be caused by <WSD>Briseis</WSD>' abduction on Agamemnon's order, and ends shortly after Achilles sleeps with her once again in his tent (24.675-6). 
Meaning of the word marked with <WSD> tags:  A legendary figure who features in the "Iliad"; a princess granted as concubine to Achilles after the sacking of her city, Lyrnessus, before the beginning of the story.