Fish Speakers in Heretics of Dune and Chapterhouse: Dune.
What happened in the 1,500 years after Leto II's death?
Following the death of the Tyrant, a Fish Speaker Council—a democratic bureaucracy—took control of the core of the old Atreides Empire. However, the Bene Gesserit viewed themselves as superior to this Council, often implying that the Fish Speakers held no monopoly on Siona genes.
When Duncan Idaho, consort of Siona, revealed the location of the Tyrant’s hidden melange at Sietch Tabr, the Fish Speakers claimed most of it. However, they ultimately squandered this valuable resource through petty conflicts, poor judgment, and general mismanagement—events that history would largely forget. While the Fish Speakers and their formerly obedient priesthood continued to enforce reverence for Leto’s Golden Path, this eventually degenerated into a system of pervasive compulsion.
With the Bene Tleilax breaking the spice monopoly through axolotl tank-produced melange, the Fish Speakers allied with Ix, finding common cause with them. Even during the Scattering and the Famine Times, Fish Speaker auxiliaries and splinter factions persisted as an extension of Ix, supposedly upholding principles of truth and justice. However, during the Famine Times, the Fish Speakers were cast out, with some disappearing into the Scattering.
On Rakis, the Fish Speaker ritual of Siaynoq degraded into an overly energetic and meaningless spectacle known as the “Dancing Diversion.” Meanwhile, in the Scattering, certain Bene Gesserit Reverend Mothers and exiled Fish Speakers, facing extreme circumstances, formed the Honored Matres—a tyrannical autocracy. Elsewhere, the Roxborough family of Lernaeus emerged from the union of Fish Speaker and Atreides bloodlines. Reverend Mother Janet Roxborough, a descendant of this lineage, was the mother of Bashar Miles Teg, who would go on to father Mother Superior Odrade.
What of the Present in Heretics of Dune?
The Tleilaxu have covertly infiltrated the highest councils of both Ix and the Fish Speakers, deploying new, undetectable Face Dancers. Meanwhile, the conditioning of the Rakian priesthood has deteriorated, and the Fish Speakers, having been distanced from their former devotions, now wield little influence. What influence they do retain has largely fallen under the subtle manipulation of the Face Dancers.
When Odrade released the Atreides Manifesto, both the Ixians and Fish Speakers were alarmed. However, she dismissed their concerns, remarking that they "hear the noise of God everywhere." On Rakis, the Fish Speakers maintain a small trading and espionage delegation, now composed of both men and women. Though men, including members of the Rakian priesthood, serve only in an advisory capacity. Odrade foresaw that both Ix and the Fish Speakers would decline together, predicting that they would be cast into a past that humanity would ultimately leave behind.
What of Their Mythology?
The Fish Speakers are remembered as the ancient army of God, cast out during the Scattering. They remain an all-female force, with men serving only in subordinate roles.
Other Stuff Lol
Gammu Keep was originally a Fish Speaker Command Center, abandoned during the Scattering.
The Tleilaxu reportedly captured a Fish Speaker who spat on Waff, condemning him as vile and pretentious.
The structure surrounding the Great Square of Keen, which now houses the Rakian priesthood, was once a Fish Speaker Center, later outfitted with Ixian technology.
At some point, Duncan Idaho was killed by a Fish Speaker wielding a knife.