Marie Louise Mignot

Marie Louise Mignot was a French literary figure. She was the daughter of Voltaire

Voltaire

François-Marie Arouet , better known by the pen name Voltaire , was a French Enlightenment writer, historian and philosopher famous for his wit and for his advocacy of civil liberties, including freedom of religion, free trade and separation of church and state...

's sister, marrying his material aid Denis in 1737, giving rise to her married name of Madame Denis. After her husband's premature death in 1744, she was taken in by Voltaire and became his housekeeper, hostess and companion. She also adopted his protégée Reine Philiberte de Varicourt

Reine Philiberte de Varicourt

Reine Philiberte Rouph de Varicourt was a French lady of letters. The sister of Pierre-Marin Rouph de Varicourt, she was spotted by Voltaire during his stay at Ferney - he made her his adoptive daughter, married her off to the Marquis de Villette and gained her entry to the...

 when the latter's marriage to the marquis de Villette foundered on his homosexuality.

She refused to follow Voltaire to the court of Frederick II of Prussia

Frederick II of Prussia

Frederick II was a King in Prussia and a King of Prussia from the Hohenzollern dynasty. In his role as a prince-elector of the Holy Roman Empire, he was also Elector of Brandenburg. He was in personal union the sovereign prince of the Principality of Neuchâtel...

 and only re-joined him at Ferney, where they lived as a married couple (though Voltaire was in love with her, they never married) until Voltaire's death in 1778, on which she inherited the majority of his estate. However, preferring Paris society, she sold off the chateau to move back to Paris.

Sources

• http://www.visitvoltaire.com/v_madame_denis.htm