Credit: JACEY

The Chinese had a tradition about eclipses. Such things happened, they said, when a dragon tries to swallow the Sun: but the dragon would go away if people shouted at it. The Chinese were, of course, correct. There really are dragons that swallow suns, and they will go away — but you have to shout very loudly indeed.

The first signs of dragons came in 2618 of the Common Era (Nebular Year 4667532109 ± 1044 Calibrated), when several nearby stars ceased to exist. The first were red dwarfs far beyond naked-eye visibility.

A greater disturbance came in 2633 with the extinction of Lac 9352, a ninth-magnitude class-M2 dwarf less than 12 light years from the Sun. This star had three Earth-like planets that the Yerkes Automatic Heliospheric Optical Observatory (YAHOO) was mapping, when the star simply vanished. Instrument malfunction was blamed at first, but analysis of YAHOO images taken just before the event showed several black shapes converging on the star. And then, in 2634, Sirius vanished.

After that, things happened very quickly. After centuries of quarrel, the various schisms of humanity agreed to move the entire population of the Solar System into spun-geode asteroid habitats. In 2667, humanity started to quit the home of its birth.

Only after the complete depopulation of the System, and the observation (in the rear-view mirror, as it were) of packs of dragons approaching the Sun — were other seemingly unrelated facts considered. The Exodus Fleet was a vestige of a species reduced by a disease which was only much later connected to the plague of dragons.

The first case of postembryonic oolithic petrosis (POP) was recorded in a military hospital on Phobos in 2596 during the Second Palladian War — humanity's final internecine conflict. POP was, at first, thought to have been a contagion bred in the death camps of the late Director of Pallas, Napoleon Ireneo Funes III.

The first victim of the disease stiffened, as if frozen. His skin became covered in scaly welts that grew until they became confluent, swaddling him in a jet-black shell of adamantine hardness. At first the shell measured the contours of the body beneath, but then contracted to become a perfect, utterly inert, X-ray-opaque sphere 35 centimetres across. The corpse (if that is what it was) was dissected — but the contents were found to be a gelatinous matrix secreted by roving amoebocytes.

Other cases of POP came to light around 2600, at first in ones and twos, and then in whole communities. Despite intense work, no cause or trigger was identified. After about 30 years, POP took off in a terrifying, surging pandemic. By 2632, the populations of the Moon, Iapetus, Mercury, Callisto and Australia ceased to respond to communication. A Mesoamerican expedition to Britain in 2635 reported the country deserted, the population reduced to quiescent, black spheres.

By 2667, the population of the Solar System had shrunk to the two billion of the Exodus Fleet — the remainder left behind, the unresponsive globes thought to represent the terminal phase of POP. The last habitat in the Exodus Fleet crossed the heliopause in 2699.

Finally left to themselves, the spheres — the remnants of nine billion souls —changed. The gelatinous contents reorganized and developed. Genes in the innocuous-looking amoebocytes — genes silent for the entire span of organismal evolution and thought to be ‘junk’ — were, at last, transcribed. Within the core of each sphere, matter itself changed its shape, unlocking tiny doors into the heart of the cosmos.

In 2815, the Alpha Centauri system was consumed by a pack of at least thirty thousand dragons. When the signal reached the Solar System in 2819, there were no eyes to see. But it did not go unnoticed. As if on command, nine billion spheres cracked open. As one, they rose into space, each surrounded by an actinic aura and spitting gamma radiation. As if choreographed, nine billion spheres converged in space to form a cordon around the Sun.

In 2845, dragons entered the Solar System and joined battle. The dragons were defeated, but at great cost. The effect on the Sun of absorbing 30,000 dragon carcasses, each one an organized lattice of neutronium, was predictably catastrophic. The Exodus Fleet was hurried on its way by a supernova blast wave. Even had it wanted to, humanity had no home to come back to.

Years later, we observers on the Exodus Fleet finally put the facts together. The key was found in ecology. Over decades, ecologists had amassed cases of prey species which, when threatened by even a hint of an approaching predator, would change dramatically in form and turn against the aggressor.

The first brood of dragons hatched when the Universe was born. The living creatures on the early generations of planets were easy prey, but natural selection worked its remorseless logic. Planets of species evolved to fight dragons by generating castes of dragon slayers, leaving a small inoculum to spread the species to other planets, other stars.

We were just such an inoculum, furthering life in the cosmos, keeping one step ahead of the dragons. POP was not a disease. It was part of the natural order of the Cosmos. And so will it be until Ragnarök.