"According to the law, what is to be done to Queen Vashti, because she has not performed the command of King Ahasuerus delivered by the eunuchs?"
This question by the king of Persia forms the basis of events that creates the unique sovereign drama of the book of Esther. It began with a marital spat. At a massive royal party, queen Vashti refuses to be displayed like the trophy wife that Ahasuerus thought he had. And this disdain tarnished her value in the sight of the king. She went from being camera candy to being a profound embarrassment.
I find it amusing that the way in which human beings act has not changed much in a few thousand years. Ahasuerus and Vashti could represent a Hollywood marriage today. Everybody's personal egos drove the relationship. Vashti proudly refused to be the king's trinket. Ahasuerus had a sense of wounded pride that drove him to end the royal marriage by decree.
And in the book of Esther God sovereignly works in human beings just as they are to bring about His saving purposes. He would bring His will to Persia through the actions of an obstinate king and through a proud king's wounded macho dignity.