When a Rhocropolis falls under control of the Sanguine, it rarely survives as part of a collective. The imbalance of power forces other Rhocropoli to resist threat of complete cultural breakdown as Sanguine memory systems disembowel the theocracy and narcissism of identity politics that drive an industrial-era culture. Jobs become obsolete. Slavery becomes a crime against the memories of all who witness the suffering of peonage and bondage. Because the Sanguine can feel the pain of those they rule, there can be no peace.
Even so, the number of candidates for conversion are very limited as products of an industrial era culture, and entire populations are culled to suppress confronting the discovery of Sanguine blood and surveillance technology.
These Rhonin Sanguine forces eventually find themselves in conflict with the Rhocropoli who want to sustain the old ways and the war, and assume command of an entire Rhocropolis.
While the Sanguine themselves are very hard to disable, the Rhocropolis is far more vulnerable to attack and a powerful weapon to move ordinary people away from the systems of government and law based on the gulf between claims and direct memories.
To protect their way of life, the industry of the Rhocropoli and their masters move to destroy the Sanguine fortress. No nation or empire will give shelter to such a threat. These isolated islands become rebel strong points, and rhonin in a system of control.
A Rhonin possess such a weapon, even if immature, can provide a gathering point for others against the established military forces of industrial population control and slavery.
Most Sanguine would be wise to simply abandon such a vessel or destroy it, but the young often do not have the capabilities of written about in The Prayer of Blood. What they know - from their lives as slaves - remain in many ways these symbols. And so the Rhonin Fortress - the Black Rhocropoli - remain a force against the empires that regard their very secrets as a betrayal to the tentative peace and prosperity for the few sustained in the other lifeboats of the pre-war era.