Who is Marquise from Ourika: An English Translation and what is their importance?

The marquise is a friend of Mme. de B. She was a bleakly practical lady with an incisive mind. She was frank even with her friends, as well as inquisitorial and persistent. She was the least agreeable of Mme. de B's circle, and Ourika was frightened of her. One day, the marquise approached Mme. de B and, after praising Ourika, demanded to know what Mme. de B meant to do with her. She claimed Mme. de B was making Ourika's future misery certain because since she was educated, Ourika would never want the type of man who would marry a black woman. She claimed to have Ourika's interest at heart, accusing Mme. de B of destroying Ourika's happiness. Ourika overheard this conversation, and it led to her despair, which eventually caused her illness and death. Years later, the marquise confronted Ourika, asking the reason for her unhappiness, but the marquise disbelieved Ourika when she cited her race and social status as the cause of her misery. Instead, she accused Ourika of being sad because her doomed and insane love for Charles made it impossible for her to accept her blackness. The marquise's accusation caused Ourika to collapse into an illness that nearly killed her.