She has various aliases – Charlotte Backson, the Comtesse de la Fère, Anne de Breuil, but her most frequent epithets throughout the book are "tigress," "demon," "panther," "lioness," and "serpent." By comparing her to animals and demons, our young heroes are deliberately downplaying her humanity in order to rationalize her eventual execution. They would never treat any "proper lady" in this fashion, so they seek to establish that her actions lie beyond the rules of established conduct.
Milady is intelligent and ruthless. Her many crimes reflect these personal qualities: as a young nun, she seduced a young priest and convinced him to steal from the church; later she seduced the son of her jailer, then married the Comte de la Fère (Athos) without revealing her criminal past; she re-married an English lord (the brother of Lord de Winter) who died under mysterious circumstances shortly thereafter; she attempted to have D’Artagnan assassinated on two separate occasions; she convinced John Felton to assassinate the Duke of Buckingham; she successfully poisoned Constance Bonacieux. Milady is a classic femme fatale, and in a sense embodies men’s deepest fears. She shamelessly uses her beauty to accomplish her goals, and uses her voice in particular to lure and manipulate men. As such, her character calls to mind the sirens in The Odyssey, whose alluring voices drive men to their deaths. In a similar fashion, Milady’s beauty and seduction results in men’s lives being ruined.