Corysta

Corysta was a Bene Gesserit sister sent to the punishment planet of Buzzell to harvest the cholister-producing soostones of its oceans. Exiled for trying to keep a child against the wishes of the Sisterhood, she later raised an abandoned Phibian boy and survived the conquest of Buzzell by the Honored Matres, ultimately serving the combined New Sisterhood under Murbella. (Sea Child; Hunters of Dune; Sandworms of Dune)

Exile to Buzzell#

Corysta had been ordered by the Sisterhood to seduce and conceive a child with a particular nobleman from a wealthy family. Contrary to the order's wishes, she decided to try to keep her daughter after giving birth. The child was taken from her, and Corysta was sent to the water-world of Buzzell to live among other acolytes who needed penance, harvesting the soostones that yielded cholister. (Sea Child)

Sea Child#

When the Bene Gesserit lost control of Buzzell to the Honored Matres, Corysta and the other sisters were placed under the hard taskmaster Skira. Like all Honored Matre leaders, Skira was cruel and unyielding, and she set Corysta under the control of the half-human, half-fish overseer Phibians. One day Corysta discovered an abandoned Phibian child that had been marked for death by the Phibians of the seacoast. Having lost her own daughter to the Sisterhood years earlier, Corysta took the child back to her hut and began raising the young male, whom she named Sea Child. (Sea Child)

When Skira eventually discovered this, she battered and bruised Corysta for the location of the hidden no-ship world of Chapterhouse, the Bene Gesserit homeworld. Corysta refused to tell her. Skira carried Sea Child to the ocean's edge in a threatening manner, but a group of Phibians emerged from the water and, though they saw the mark of abandonment the boy bore, accepted him back into their society because Corysta had nursed him to health and taught him the basics of swimming. (Sea Child)

The New Sisterhood#

Quite unexpectedly to Corysta, Murbella, Mother Commander of the combined Matre and Gesserit organization known as the New Sisterhood, landed on Buzzell to retake the world from rebel Honored Matre groups who refused to unite with the combined order. After destroying the Matres' orbital defenses, Murbella and her Valkyries landed to confront all the women on one of the planet's lonely islands. Corysta was lined up with the others, including a protesting Skira, as Murbella demanded to know who oversaw the soostone operations. Murbella killed several Matres until Corysta stepped forward and offered to share with her. Through the sharing, Murbella learned of Corysta's loss of two children and her knowledge of soostone harvesting, and made her commander of the island. (Hunters of Dune)

The Seaworms#

Years later, without Corysta's knowledge, the ghola of the Tleilaxu Master Tylwyth Waff introduced his version of the genetically altered sandworm, called Seaworms, into the oceans of Buzzell under the guidance of the Spacing Guild. After a short time the ferocious creatures began feeding on the Phibians who harvested the soostones, leaving Corysta perplexed. When Waff returned to Buzzell a year after the seeding, Corysta was present on the docks as he had a giant dead Seaworm brought in. He examined its organs and functions but answered none of her questions, and after extracting a great cache of ultraspice from one of the creature's organs, he departed the world for a waiting Guild ship without a word of explanation. (Sandworms of Dune)