Alraune is a top class demon in Hell, and actually has her sights on becoming its queen. Bayonetta, on a journey to save Jeanne, finds her way to the villainess's domain. Alraune tells her that Jeanne's soul is quite delicious, and has it trapped inside of her body. When she see's that the heroine has allied herself with Madame Butterfly - a hated arch nemesis of the villainess - Alraune attacks her in a rage. Once defeated, Bayonetta moves to kill her, but Rodin intervenes, and violently transforms Alraune into a weapon for the heroine to use instead.
From the in-game bio: "A woman who doused herself in mandrake poison and took her own life as a means of getting revenge on the husband who left her. The poison continued through her skin and devoured her soul. Consumed by delusions and hallucinations, she was at last reincarnated in Inferno. Myth places her as the young daughter of a noble estate, but none of her past visage can be determined from her current demon form. She searches the bottom of hell for the most exquisite souls, then injects poison into their nerves to make them eternal "lovers" at her palace. Insatiable desire and obsession have painted her heart so thickly that she will never know peace. Not even with the sacrifices of a thousand souls, or a million..."