The future bane of the Frontier and so many other species, evolved on a pleasant world orbiting a typical G sequence star.  Moonless and with stable tectonics, their birthplace was pretty much a global wetland.  Only an occasional line of hills breaking up the seemingly endless flat calm seas of aquatic flora.  The world's fauna had not even passed the invertebrate stage when the "proto-satha" started tickling sapient's ribs, so to speak.  Proto-satha tribes developed and began following the migrations of "great worms."  Feeding on the deep and tender roots their stately passage exposed, and on their carcasses when they died.

        This became a symbiotic relationship between the proto-satha and great worms.  Who were developing their own sapience too.  The tribes guided and cared for the great worms who, in turn, provided everything they needed.  Centuries turned into millennia and, in time, the proto-satha were not only following the great worms, but even living on top of them.  Festivals occurring wherever tribes crossed paths.

        Life was good, and it would not last...

        In a nearby system another species had found its way to sapience.  A reptilian race which had clawed its way to civilization and beyond their world.  Unlocking the mysteries of FTL, they reached to other stars.  The first sapient race they encountered was the proto-satha.  They saw the chatty worms as primitives, needing to be taught "civilized" ways.  Before long this turned into land grabs and outright slavery.  Mines and factories quickly followed, fouling the waters and skies.  Much of the world's once plentiful flora and fauna were driven to extinction.  Including the great worms.

        The proto-satha tried to resist, to fight back, but they were no match for the reptilian's technology and brutality.  Beaten and broken, the proto-satha might have been forever doomed if their master's arrogance didn't court catastrophe.  Encountering another sapient race they discovered, much to their regret, that they were hardly as naive as the proto-satha had been.  A bloody war followed.  Which became a brutal stalemate.  The conflict dragged on and on, with casualties climbing higher and higher.

Tiring of this seemingly endless war, their masters began having their slaves fight for them.  At first it was simply as cannon fodder.  Yet as the campaigns ground on, the reptilian's slowly turned over more and more of their war machine to their slaves.  Wrapping themselves in decadence, protection from the truth of how high a price their pride was charging.

In the midst of this hopelessness, a Messenger appeared among the slaves.  Proclaiming that the last Great Worm was calling to them from beyond its grave.  Calling them to punish the reptilians for their heinous crimes.  Calling them to protect the Great Worm's children, wherever they might be, from the ravages of other befoulers.  The Messenger was smuggled from fleet to fleet and legion to legion, gaining converts everywhere he went.  And where the Messenger did not go?  Its disciples would.

        A new religion was born among the wreckage and ruin.  For a broken and brutalized people, the call of the Great Worm was like the sweetest honey.  Giving them purpose and showing they were part of something greater.  Only those who had cared for the great worms could be trusted with so sacred a task.  The Followers' numbers grew but not all slaves felt the calling.  Eventually the Messenger was betrayed to the reptilians.

        The masters began a great purge, but feared weakening their defenders too much, or finally goading them into rebellion.  The Messenger died, but its disciples carried its message onward, the Followers' ranks ever growing.  More purges followed, each teaching them how to hide their faith more and more in the shadows.  In hiding some of the faithful would inadvertently begin altering the message.  Focusing more on one gospel or another.

The hidden communities became sects.  The beliefs of each, somewhat distinct from the Messenger's teachings.  They openly battled their masters' enemy, while covertly preparing, and converting.  Across the stars, the Followers' and their Sects waited, for a sign...

        That sign came when the reptilians' implacable foe.  Finally became more, well, placable.  Exhausted, they agreed to peace.  The relieved reptilians finally felt safe enough to start disarming the slave fleets and legions.  Word of this spread like wildfire and the Followers knew they might never have another chance.  Spreading as rapidly as the warning, an uprising began.  The sects turned their guns on their masters, and any slave who refused to join them.

Reptilian space dissolved into chaos as their slaves ran rampant, attacking anything and everything.  The reptilians, and the slaves who remained loyal to them, fought hard.  Yet they were vastly outnumbered.  The reptilians started calling the Followers, "sathar," which meant "fanatic" or "zealot" in their tongue.  The sects liked this slur and adopted it as their own.

Soon the reptilians were driven back to their homeworld.  Once they were done with it, only a radioactive wasteland of craters remained.  Yet instead of peace, the sects discovered themselves in another war.  Their master's enemy sought to take advantage of a supposedly weakened foe.  Instead, they found the "sathar" to be much more dangerous without a master's leash.  Before long?  Their world was also turned a radioactive husk.

        As the Followers tried to reclaim the paradise of what had been.  The disciples sent the sects across the stars.  Where they found sapience?  The sects studied it, and brought their findings back to the disciples.  The disciples would study and debate the evidence, to determine if they were befoulers.  If they were?  The sects brought the wrath of the Great Worm down upon them.  If they were not?  The sects would protect them from the tainted or, rarely, even offer guidance.

Sometimes the sects found a race, or collection of races, strong enough to delay the disciples' judgement.  For them?  The sects remembered the hard lessons taught by the reptilians and first used the shadows to move within...