Isillinde, a Tsol'aa of noble birth, served for many years as High Priestess of Ourania. During the events of the Eternal Night, she revealed herself to be a member of the secret astronomical society led by Tavarius. She accused the highest members of the society of plotting to give only themselves immortality, and asserted that Tavarius, discovering this intention, had moved quickly with Isillinde's support to harness the power of the sun himself. Before the ward of power on Mount Nicator, she declared to the assembled crowd that it was their intention to grant the gift of immortality to all people. "A short time of darkness is a small price to pay for eternity," Isillinde reassured the crowd sweetly. "There is nothing in the night to be afraid of."
After the true nature of Tavarius and his plot was revealed, the extent of Isillinde's betrayal became obvious, and she was cast out of the Order of the Moon. Decades later, she was slain mercilessly by Mukamuttara, after the moon spirit had escaped from the confines of her meteorite originating from Lunastra.