Mireille

Mireille was the leader of the French Assassins and the lover of the famous bandit Cartouche.

In 1721, when her lover was caught by the authorities and sentenced to be broken on the wheel, Mireille decided to save him. She bribed the executioner and joined the crowd, watching her pawn using pig blood to make them believe that Cartouche's internal organs had exploded under torture while he had in fact survived. Cartouche healed and discovered that Mireille was an Assassin and also their leader, he was then trained and joined the Brotherhood. Cartouche wrote his story and Mireille intervention into a diary, which he passed on to the Assassins.

Reference

 * Assassin's Creed: Unity