Marquise de Merteuil is femme fatale of Les Liaisons dangereuses and is married noble woman who seeks revenge against her lover who left her to marry 15 year old Cecile de Volanges and she approaches and teams up with Vicomte de Valmont plotting to correspond other women for downfall. She was also manipulating men out of boredom to sleep with her for enjoyment, She and Valmont were lovers before because he was nephew of her friend and afterwards she had affair with the Count thus she left Valmont turning him into notorious womanizer who finding the challenge too easy from Merteuil. Two of their victims were Madame de Tourvel who is the wife of politician who has remianed virgin and faithful to her husband and Cecile who had been betrothed to Merteuil's former lover but she was in love with her music tutor Danceny (who also feelings for her) and Merteuil suggests Valmont to play with Celice as begins seducing her which led to loss of Celice's virginity.
When Cecile confessed to Merteuil about her experience of losing virginity to Valmont by guilt that if her mother found out as Merteuil encourages her to married her lover means Danceny as male mirtess.
Merteulli's next victim was Madame de Tourvel who stayed in Valmont's aunt while her husband was away
The character Kathryn Mertueli of the 1999 film Cruel Intentions is based on Marquise