There were no signs, their numbers dwarfing the combined might of every interstellar state across our history, they came without warning, without decorum, without explanation. The only communication received from their innumerable vessels was a single phrase repeated again and again that took our most brilliant xenolinguistist months to decipher.

“Impure”

Months into their relentless assault the "unwelcome" finally came forward. Extragalactic entities that had silently slipped into our galaxy trying to escape the very force that now assailed our stars. From them we finally learned of our foe.

Once they had called themselves Humanity, a race of tradespeople with penchant for diplomacy and an uncanny ability to adapt to most environments they found themselves in due to their harsh homeworld. That is all they aspired to be, a simple yet proud people making their way in the universe. Perhaps they could have stayed the course of diplomatic traders if not for their encounter with the Dominion. An interstellar imperium that controlled nearly a forth of the Galactic rim, the Dominion in their unquenchable greed and need for labor, struck down the human’s fledgling collection of star nations and placed their entire species in chains.

But the Dominion failed to realize was the paradox that was the Human race. The worse the environment, the crueler the treatment, the harder their lives, the taller those that endured it would stand. Humanity thrived in hardship forcing only the best attributes to remain to ensure their survival and propagation. This evolutionary adaptation was meant to be temporary in the face of hostile environments in order breed those who would facilitate the eventual taming of said environment. But what if the environment remained harsh indefinitely? What if Humanity was forcibly kept in a constant state of cruelty, and thus, genetic improvement?

The Dominion did not care as all they saw was a workforce that improved the harsher they were treated. Soon after their assimilation torment and excruciating conditions became standard human conditions.

For centuries the Humans toiled away as disposable labor, experiencing the most depraved and sadistic treatment imaginable. Other Stellar nations condemned the Dominion’s acts but in the end they proved too weak and discordant to truly do anything to stop them. Abandoned and enslaved something fundamental within Humanity shattered alongside their freedom and hope. Whereas any other race’s will would have been crushed within a handful of generations, Humanity’s ancient tendencies, long suppressed, allowed them to spitefully endure their new master’s cruelty.

Gradually, silently, inexorably a new creed was forged, galvanized with their festering abhorrence of all that was not their kin. Adherence to this new dogma became a natural as breathing and in their eventual violent emancipation from the Dominion a new human power arose from the ash and dust of the fallen civilization, the Ecumenicate of Man.

Many rejoiced at the collapse of the great empire that had kept the rest of the galaxy in fear. Several envoys were sent to the Ecumenicate to establish relations. They were met with utter silence. No human ship acknowledged their hails, no human world allowed them to land, and the borders of the new nation were unceremoniously closed without explanation. For two hundred standard years many believed that was the end of their story. But then came their belated decree to the galaxy that abandoned them.

With a chorus of a trillion throats the Human race declared all other sapient life’s damnation.

They declared them.

Impure.

When the spark of hatred so tenderly cradled in their hearts for a millennium was finally lit Humanity’s anger was made manifest and entire sectors burned to ash. History’s erased, stars collapsed, generations slaughtered, empires extinguished. Until finally, only they remained.

Everyone that was left took to the void between galaxies in a desperate attempt to escape the Human Tide unleashed by the Dominion’s foolish greed, but as they had done for their entire history, Humanity followed their quarry with the persistence of demons.

There can be no recourse with the tides coming. You can erect great walls to hold back the waters, dig holes it will have to fill before advancing further, but it will arrive all the same. All you can do is watch it rise.