Haman's Promotion and His Plot in Esther 3
Haman held the highest seat at Xerxes' court because the king put him there. The passage traces how that honor curdled into a scheme against an entire people.
Who Was Xerxes' Father? Esther 1 Gives No Name
The opening of Esther introduces a king called Ahasuerus and describes his vast empire and lavish feast, but it never names his father. Any link between Ahasuerus and the Persian king history calls Xerxes is reconstruction, not something the text states.