Who was Sophia?

In the book, Sophia is a beautiful white mouse who catches Amos' fancy. Amos, of course, is the book's narrator; he is a mouse who accompanies Ben Franklin on his journeys abroad.
We are introduced to Sophia in Chapter 11. Amos tells us that Sophia is originally from the Court of Versailles and that she lives in Madame Brillon's headdress. As Amos converses with Sophia, he becomes enamored with her. Sophia is intelligent, well-educated, and cultured.
In due time, Amos learns that Sophia's husband (a member of one of the oldest mouse families in France) has been exiled to Philadelphia. Meanwhile, their seven children are captives at the court of Versailles. Sophia pines for her children but can do nothing to rescue them. After she herself was banished from the court at Versailles, she became Madame Brillon's confidant and adviser. Because Madame Brillon makes frequent visits to the court at Versailles, Sophia has been able to discover that her children are imprisoned in a cell beneath the Queen's throne.
As the chapter ends, Amos promises to help Sophia. In Chapter 13, with the help of fifty of John Paul Jones' sailor rats, Amos is able to free all of Sophia's children from their cell in the court of Versailles. Sophia's entire family is eventually reunited in Philadelphia.