Gabrielle de Polastron, duchesse de Polignac is a singer of the Palace of Versailles, but she does not live there and is seen as a conniving snake to all the nobles in Versailles, who comment that while she has the voice and looks of an angel, she is cold and ruthless. Marie Antoinette listens to her and quickly makes her best friend. She impelled Marie Antoinette to bet in clandestine casinos, without the permission of Marie Antoinette's husband, King Louis XVI. She manipulated the queen for her own benefit and made the queen believe that lies would fix her difficult situations. Following her advice, Marie Antoinette lied and announced that the heir of France was on way. In order to remedy the situation, Polignac blamed the death of the heir on Lady Oscar.
She is the biological mother of Rosalie, who she bore and gave birth to at age fifteen and went by the name Martine Gabrielle de Goulard. It is uncertain if Rosalie's father was the late Count de Valois, but it is speculated that she was probably with a servant boy when she got pregnant with Rosalie and probably gave her away to protect her reputation and her family's for having a child out of wedlock and with a man of lower class so she can still find a rich suitor to marry. A few years later, she married the Duke of Polignac and became the Duchess of Polignac, while changing her first name from Martine Gabrielle to Chalon to make sure no one knew of her mistake from her youth, and eventually had another daughter, Charlotte, who was traumatized by her mother's plan to marry her to the Duke de Guiche, a known pedophile, to help the family's financial problems since her father was not a very rich noble. Charlotte, fearing what will happen to her if she marries the Duke de Guiche and wanting to be clean and pure like the rose after the Duke kissed her hand, loses all reason, and commits suicide, jumping from one of the towers of the Palace of Versailles. She died without knowing that she had a half-sister.
In a desperate attempt to save the family fortune, the Duchess blackmails Rosalie into coming to live with her by saying she will have Oscar arrested for being an accessory to the historical crime of France "The Affair of the Diamond Necklace" by letting the sister of the accused criminal, Jeane de Valios, live with her. Rosalie, wanting to protect Oscar, agree's to go with her. Rosalie finds out that the Duchess wants her to marry Duke de Guiche, the man that caused Charlotte to kill herself, and she escaped and has cut ties with the Duchess and Rosalie ends up falling in love and marrying Bernard, another one of Oscar's friends.
During the Revolution, Madame Polignac escaped along with other nobles to avoid being tried for their crimes during Marie Antoinette's reign. In real life she died from illness at the age of thirty-three.