Ermenshrew Blathereen's daughter killed and disguised herself as Warder Blanc, a prison guard in Detention Centre 6 on Justice Beta in 2501. As Blanc, she earned a reputation for being sadistic, and often organised "welcome parties" in which new inmates would be beaten upon arrival to break their spirit.
She, along with Warder Norris, was one of the first guards Rose Tyler encountered while imprisoned on Justice Beta. The Blathereen feigned friendliness, before attempting to kill Rose by putting her in a room with Kazta for fun. She later killed Norris after discovering he was an undercover agent, and revealed her true identity to Rose before once again trying to kill her, although she escaped. The Blathereen also killed The Governor in order to have another Blathereen replace him. However, Kazta and Callis Fel-Fotch Heppen-Bar Slitheen, who was disguised as Maggi Jalovitch, later started a prison riot after Kazta saw the Blathereen disguised as Blanc outside of her disguise and Callis revealed the Governor had been replaced. Both Blathereen were beaten to death by inmates during the riot. (PROSE: The Monsters Inside)