At last, d'Artagnan has met the famous Musketeers: Athos, Aramis, and Porthos. Though d'Artagnan still has much to learn, the Musketeers sensed that she could be entrusted with the future of Lutetia. They began to teach her the techniques of the royal guard and looked forward to the day when they would stand as not three, but four Musketeers with d'Artagnan as their leader.
d'Artagnan is a fictional character, and the main character in Alexander Dumas' d'Artagnan Romances, a series of french novels with the most famous being The Three Musketeers. In The Three Musketeers, d'Artagnan chooses to leave home in order to join the Musketeers of the Guard, and eventually befriends the titular three musketeers of the novel, Athos, Porthos, and Aramis.
Dumas' popular character is in turn a fictionalized account of the life of Charles Ogier de Batz de Castelmore, Comte d'Artagnan, a captain of the Musketeers of the Guard who served Louis XIV.