They appeared within our cities.
In an instant, first came the watcher, with the filth-monger close behind. The emperor and the ultimate puppet; the highest and the lowest. From our rooftops and spires, they controlled our minds. From our subways and our sewers, they polluted our bodies.
The bond between the watchers and filth-mongers held firm as they pulled at one another. Their tension kept the ripped-wall tear ajar, and through that seam poured forth their followers, which sprawled on, and on, and on.
These strangers were not quite like people, or like animals. Their bodies, though superficially simple, were composed of materials we could not recognize. They could move without a muscular system, react to the world without a nervous system, and speak without vocal chords. They did not require respiratory, circulatory, or digestive systems to process or regulate energy. They seemed more like natural phenomenon than living beings.
Their kind could always be identified, however – mostly by their shape, and mostly by their patterns, and mostly by their eye markings (some of them swirled crazed, and others, cried black ink or blood), and by their claws, and by their teeth.
But always by the way they changed the world around them, and what they did to us.
And always, they kept coming.