In the Dungeons & Dragons role-playing game, Lady Fierna is the ruler of the Fourth Layer of the Nine Hells of Baator. She is the daughter of arch-Duke Belial and his late consort Naome, and currently shares the rulership with her father.
Fierna, who wasn't into politics in the first place, accepted this treatment and decided at first to merely enjoy what her brand new status was granting her. She used to spend most of her time in her palace, having sex and fun in her eternally blazing pit of lust and leaving the concern of governing and managing to her parents and her consort, the pit fiend Gazra. She would only come out to do her father's commands and to attend the yearly meeting of the arch-Lords in Nessus.
Fierna changed her mind about ruling Phlegethos recently, when she developed a friendship with Glasya, Asmodeus's daughter who is now in command of Malbolge, the Sixth plane. Fierna looked up to her and began to understand the true meaning of rulership. Thus, she has become a little more serious about her actual job. Belial, who won't relinquish his power, dislikes having his daughter discussing his decisions and acts to remind her who's making the rules.
Gossip says that Belial and his daughter are having an incestuous relationship. This rumor grew stronger after Naome's death, even though Fierna has a consort of her own. The loyalties of Belial and Fierna's vassals tend to sway between the two according to the favors granted or to their own convictions about the ability of the Lords of Phlegethos.