Darth Noctyss was a very powerful Sith who could have conquered the entire galaxy, but she became focused on another goal: to live forever. She searched for long lost knowledge and relics, eventually making her way to the Sith world of Exegol. For months, she explored the deep ruins, eventually finding a mutated feral beast of a man in the depths. The creature knew what she sought and led her deeper into the citadel, eventually reaching a chamber. The chamber contain the records of Darth Sanguis, who had achieved the immortality Noctyss had sought.
Noctyss prepared the ritual and the creature, who proved to be a much needed component. She plunged her dagger in to the creatures heart as the chamber sparked with energy. She felt invigorated as her body started to shift and change while the vital energy flowed into her. But joy became anguish as her body convulsed and her spine twisted, she feared what she had done wrong. Noctyss awoke sometime later and, seeing the lifeless body of the creature with a wicked grin on its face, realized it had known all along. She had followed in the footsteps of Darth Sanguis and she was now just like him: a twisted, grotesque version of her former self, cursed to eke out a painful, lonely existence in the bowels of Exegol.