Cix-Tu

The Cix-Tu are an alien civilization in the Covenant's peripheries on the trailing side of the Orion Arm. A small empire from beyond the Sullen Sea, they're a very minor nuisance to the Covenant at large, known largely because of their slavetaking operations and their skilled surgeons. To the worlds of the Marrak Frond and the Hrelon Delve, they are a persistent and dire threat. Whole cities and small colonies have been abducted by slaver fleets, to be sold as chattel elsewhere in the galaxy.

Overview
In some ways, the Cix-Tu are a puzzle to the Covenant. Their technology is a hodge-podge of machinery bought or stolen from other spacefaring civilizations, as well as very advanced homegrown cybernetics. Their biology is largely unstudied, because Cix-Tu slavers and soldiers alike have a fanatical dedication to retrieving the bodies of their fallen comrades. Their religion is arcane and sparse, and has little to do with the Forerunners. Both their slaver fleets and their military seem to be controlled by the same government, the Imperial Directorate of their homeworld.

After the initial encounters with slaver fleets, the Covenant response to the Cix-Tu threat has been to beef up patrols along the Sullen Sea, and to purchase back enslaved Covenant citizens. There has been no talk of invading Cix-Tu territory, because they are thought to be a useful buffer against whatever empire lies beyond. This changed during the 22nd Age of Doubt in 2367, when a Cix-Tu fleet pushed into Covenant territory and begged for political asylum. This is when the full truth of Cix-Tu civilization was revealed to the galaxy outside. An interesting quirk of Cix-Tu biochemistry is that their bodies do not use hormones to regulate their bodily functions. Instead, they cultivate an ecology of viral agents. This makes cloning organs nearly impossible, even in laboratory conditions. It also means that autoimmune diseases are endemic to Cix-Tu. Their median lifespan is thirty-five years. Bionic transplants can push this to forty-three years. Centuries of genetic engineering and gene therapy development has pushed the median lifespan to fifty-one years. With organ transplants, Cix-Tu lifespan can be pushed to nearly a hundred years.

The Imperial Directorate maintains control over Cix-Tu civilization, because they control who has access to the organ banks, and who gets fed into them. Upstanding Cix-Tu citizens are kept alive with organs taken from criminals and political prisoners. Criminal Cix-Tu, even minor ones like embezzlers and chronic traffic violators, are sentenced to death and broken up for spare parts.

High Charity came this close to launching a humanitarian mission to put down the Imperial Directorate and liberate the Cix-Tu civilization, but then much of the fleet was diverted to ending a civil war in the Solis Nexus, and the rest were sent to a border skirmish with the Jiralhanae. The Cix-Tu threat fell to the backburner of Covenant politics, and then was all but forgotten. The Imperial Directorate slowed down slavetaking operations in Covenant territory, instead tasking military and slavetaking fleets alike with long-range patrols. Many Cix-Tu ships have been spotted prowling the worlds of the Ulannon Migration and the periphery of the Orion Complex, and may have made it as far as the Human Sphere. Thus far, their goals are unknown.

As many as five million Cix-Tu refugees have settled within the Holy Ecumene and somewhat integrated into Covenant society. They're some of the best surgeons money can buy, though most would rather not think about where that expertise came from.

Trivia
By a strange quirk of fate, the Cix-Tu word for 'Doctor' is a near-homophone with the Pan-Sangheili word for "Harvester". This coincidence greatly annoys one surgeon residing in the Shoal. He's an ophthalmologist, not a Harvester of Eyes, and you'd better not call him that to his face.