During in the Cardassian Occupation of Bajor, the prylar was a good friend of Kira Taban and Kira Meru, the parents of Kira Nerys, at the Singha refugee camp. When Meru was taken she looked out for the Kira family and was responsible for introducing young Nerys to the teachings of the Prophets. (DS9 novel: Avatar, Book One)
In 2353, Istani comforted Kira after the Cardassians took several girls from the Singha camp, including Kira's friend Petra Chan. Istani told Kira the Prophets would look after Petra. (ST - Terok Nor novel: Night of the Wolves)
By 2376, Istani was involved with the archeological excavations at B'hala where she served as part of the Site Extension group. There she discovered the lost book of prophecies of Ohalu, who 30,000 years before had described the Prophets as teachers rather than gods and was branded a heretic. When Istani translated the ancient text, she was astonished to find the prophecies to be remarkably accurate and clear, much more so than accepted prophecies. She also discovered some ominous predictions concerning the impending birth of the child of Benjamin Sisko, the Emissary of the Prophets, and Kasidy Yates. Ohalu called the child "The Avatar of Peace," and stated that 10,000 would willingly die for the child before its birth.
When Istani brought the book before the Vedek Assembly, she was horrified by their pronouncement the "heretical" book be destroyed. Istani then stole the book from storage in B'hala with the intention of bringing it to Kira Nerys on Deep Space 9. Before leaving B'hala, she met with the Emissary's first child, Jake Sisko, and gave him a prophecy she believed pertained to him and his father.
She was followed to Deep Space 9 by Vedek Gamon Vell, who was sent by the Vedek Assembly to retrieve the Ohalu Prophecies. He confronted and murdered Istani on the station's Promenade before falling to his own death. However, Istani had hidden the book before the attempt on her life, which was later found by station security chief Ro Laren during her murder investigation. Ultimately, it was discovered that the "10,000 dead" mentioned in the prophecy referred to the guardians of the book itself throughout the generations, with Istani herself being the 10,000th and final. (DS9 - Avatar novels: Book One, Book Two)