The irony of these events is highlighted by calling Haman the enemy of the Jews.
His property (which must have been massive; see Esther 3:9) was inherited by a Jewish woman! And Mordecai, for whom Haman’s gallows were intended, was now serving in the presence of the king.
1 On that day King Ahasuerus gave to Queen Esther the house of Haman, the enemy of the Jews. And Mordecai came before the king, for Esther had told what he was to her.