Hortense's Wikipedia article is here. She was brought over to England after her failed marriage to Armand-Charles de la Porte, duc de La Meilleraye. It was hoped Hortense would replace Louise de Kérouaille as Charles II's mistress at which she first succeeded. She also had relationships with Anne, Countess of Sussex and Louis I de Grimaldi, Prince de Monaco. Louise de Kérouaille returned to Charles' favor when Hortense had her affair with Louis Grimaldi.
According to Marie Mancini's Wikipedia article, "Marie captured the biggest prize of the French court: the romantic love of Louis XIV. According to Antonia Fraser's biography Love and Louis XIV, Marie's mother, Geronima, was told by a horoscope that Marie would cause trouble and demanded on her deathbed that Cardinal Mazarin should, 'shut Marie up in a convent and keep her there.'
Marie did not consummate her relationship with the Sun King. His love for her was a somewhat idealistic one, but he was so besotted that he wanted to marry her. Eventually, Cardinal Mazarin and the young king's mother, Anne of Austria, separated the couple, banishing Marie into exile and arranging for Louis' marriage to his cousin, Maria Theresa of Spain."