Neptune's Brood

by Charles Stross

  INTERLUDE

  A Thousand Years Ago

  The dying man drifts from the rippling silver mirror of the sky.

  He is almost completely dead, spine severed and circulatory system ruptured by a harpoon that sliced through the major vessels of his neck and lodged point first in the base of his skull. The gash in his throat streams a trail of emerald green circulatory fluid; meanwhile, the uncoordinated twitching of muscle groups in his arms and lower limbs hints at the coming struggle of individual mechanocytes to survive the demise of the collective. The weapon that killed him still quivers as it tries to free its blade from the cranial prison it so enthusiastically embedded itself in. But it has fulfilled its murderous impulse too well: The tightly meshed tensegrity structures of his armored brainpan grip its barbs tightly, and the weight of his dead body drags it down. Killer and victim have embarked on their final journey together, drifting down into the darkness.

  They will fall together for a very long time.

  * * *

  At first, the ceiling of the world seems close enough to touch: Waves and rippling interference patterns march across it, and small dark islands clump and drift just beneath the surface, casting long shadows into the depths. The ruby glare of the sun pierces the sky directly overhead. Clouds of semitransparent sunfeeders drift in the brightness, numerous beyond counting, hazing the water and casting dappled shadows across the silvery motiles that dart and nibble at them from below. In the pearly distance, leviathan grasses float like tenuous auroral continents, soaking up the solar largesse.

  The corpse and its killer drift down through the sunlit upper waters of the world. His humanoid body plan puts a brake on their downward progress: His terminal velocity is less than five kilometers per hour, little more than a fast walking pace on land, and thanks to his residual buoyancy, at first he falls at barely a tenth that speed.

  Fifty meters below the surface, the entangled bodies pass close to an eel-shaped motile. It sniffs the bloody trail, then closes in, clamps three sets of jaws to the wound in the body’s throat. It sucks greedily for a while, slowing the body’s fall as it extracts what’s left of his pressure circuit, but fifty meters farther down, the increasing pressure forces it to let go. Falling faster, the exsanguinated body leaves the sunlit upper reaches behind.

  It is colder beneath the thermocline, and the pressure rises steadily the farther the corpse falls from the roof of the world. The red light of noon fades to the dim purple glow of the disphotic zone. In the direction of travel, there is no light to speak of: just a darkness as palpable as a black hole’s event horizon. The waters of this zone are a-chirp with the hunting clicks and shrills of saprophytic feeders: The overlapping thermoclines above reflect tight-beam upward-directed sonar pulses back down, illuminating prey and fragments of falling food without revealing the location of the scavengers to their toothy, bug-eyed predators.

  The dead body’s muscles and viscera twitch and pulse regularly as individual mechanocytes desperately try to punch their way out through the woven, lifeless integument of his outer skin and clothing. Uncoupled and disoriented by his death, every ’cyte remaining in his body fights for itself: They’re not very smart, but they’re brighter than their purely biological antecedents, and the steadily increasing pressure of the mesopelagic zone is weakening the social contract that binds them into a body. The scavengers have noticed the presence of a meal falling through their space, and if they can’t escape soon, it will be too late.

  Three hundred meters down, the corpses fall through a school of Bezos worms. They close around the falling bodies and tighten, adhering to each other in a matlike mass. The bodies dangle from the island as the worms prod and poke at their prize, rasping through skin with their concentric circular jaws. The harpoon’s armored body is largely immune to their efforts, but the dead man’s body is vulnerable. There is resistance: Mechanocytes do not appreciate being eaten, and fight back. But they lack coordination. Their owner could have directed their collective defense, were he still alive, lending them his sense of identity and will to selfhood. But the millimeter-scale ’cytes spilling from his dead body are weak and disoriented. They defect in their hordes, spilling into the worms’ stomatogastric mills, their resistance crumbling as the worms reprogram and repurpose them, adding them to their gut lining.

  Despite the depredations of the worm colony, the body remains recognizable for another hundred meters. The worms squirm and writhe within his skin as they hunt down the remaining actuator mechanocytes and loot his feedstock exchange organs, then attempt to hack his quiescent neural trunks, wheedling the marrow techné and central neural core with recorded pleas for access and promises of repair, zombie messages harvested from previous victims. But the rich techné of the body’s marrow—the core of replicator mechanocytes from which his ordinary tissues are spawned—are either dead or firewalled, not responding.

  The growing pressure of the aphotic zone threatens to wreck the delicate intracellular machinery of the worms’ own techné, crushing paraproteins and ribofabricators into nonviable conformations: They’re locked in a race against time, desperately trying to eat their fill without being pulled down below their crush depth. Finally, the worms let their prize fall, and the now-flensed skeleton continues its descent, still wearing its bag of skin for a shroud.

  The body falls faster through the crushing pressure and chilly darkness of the abyssal depths. But it is not alone even here. Ghostly scavengers—little more than solitary, feral mechanocytes—latch onto his tough, barely digestible skin and patiently chew away, detaching dermal scales piece by piece. Gradually, his bones are laid bare to the night. There are neither lights nor eyes to witness the lustrous glory of fiber-reinforced titanium, still impaled on the point of the harpoon (stilled forever, its vestigial brain long since crushed by the steadily rising pressure), to note the elegance of his articulated joints, or the presence of the two external cranial interfaces, each still occupied by a soul chip.

  As the corpse falls, the pressure rises, and the scavengers grow scarce. Finally, nearly a hundred kilometers below the ceiling of the world, there is a creak and a brisk pop as a seam in the cranial vault gives way. A brief mushroom cloud of debris spills from the base of his skull, and the dead harpoon rocks briefly, then topples free, falling point down into the Hadean depths. (Leading the way, it will reach its destination far ahead of the other remains.) There are more creaks and pops. The long leg bones, with their buried marrow techné let go next, and millions of the most complex mechanisms ever designed are smashed to pulp in microseconds by the mindless pressure of depths for which they are not adapted.

  Hours pass, then more hours. The water grows clear and gelid in the utter darkness. Once, the utter black is broken by a pale rising glow of Cerenkov blue, roiling and bubbling with strange energies as it heads toward the surface: Then all is dark again. Hours pass, and tens of kilometers—then days, and hundreds of kilometers. Strange life lives down here, subsisting on the deadfall of Hadean dwellers whose corpses rain down from unthinkably far above. But the corpse, already stripped of anything that might be of use, is of little interest to the denizens of the deep ecosystem.

  Nearly two hundred kilometers beneath the sky where he was murdered, the banker’s bones gently grind against a rocklike surface and rebound briefly before resuming their fall.

  Twenty kilometers farther down, there is another impact, this time more final. The body has struck a cliff face of hard crystalline material rising from the darkness. There is no light to illuminate the pearly white finish of the sunken ultradense iceberg. Disarticulated by the impact, his bones tumble down the glacial cliff toward a plain of muddy debris that covers the tilted basalt plate where it abuts the ice. As it rebounds his damaged skull sheds its precious load, scattering the last legacy of his mind, stalled forever in the shock of sudden death.

  And so it is that when his soul chips come to rest on the floor of the world ocean,
their buffers are forever occupied by a meaningless exclamation of horror, by the final memory of a desperate pursuit and murder, and a debt that will never be redeemed.

  part two

  THE ABYSS

  Arrested Development

  “Will somebody tell me what’s going on?” I asked for the third time.

  “I was hoping you could tell me,” Serjeant Bull rumbled from the far side of the interview table. He sounded bored rather than irritated or amused. A retina, covering its surface, showed a montage of views of my confused arrival and interview with Queen Medea.

  “But I don’t know!” I rubbed my forehead. “All I can tell you is what happened to me. Which I’ve already done. Twice, now.”

  “Well, why don’t you tell me again?” he asked. “Start with Taj Beacon, scholar, and your awakening in the arrivals hall.”

  The worst thing about being remanded in police custody is the uncertainty; the second worst is the boredom. (Fear and pain . . . I consider myself lucky: Argos is a relatively civilized kingdom for an authoritarian tyranny, and while Medea has numerous faults, encouraging a culture of excessive brutality among her staff is not one of them. In the sunlit, nutrient-rich upper waters of Shin-Tethys, it is all too easy for disgruntled subjects to vote with their fins. Consequently, those rulers who arbitrarily torture and mutilate people do not benefit from a thriving revenue base.)

  Serjeant Bull had already taken me through my account of the events of the past year on two separate interview days—I assume they were days, for between interviews and meals my coral-walled cell had darkened—and I had told him more or less exactly the same story twice now, omitting only a few details that I deemed to be of no interest to his investigation; the communiqué from Andrea, Rudi’s ownership of a slave chip (potentially a blackmailable lever over him while he was outside the safety of his vehicle’s hull and one that I felt no need to expend prematurely), Rudi’s suspicions of Deacon Dennett’s intentions (hearsay) and so on. And so I continued, for the third time:

  “I am a mendicant scholar, halfway through a five-subjective-year study pilgrimage to visit and work with a number of my colleagues. My distant sib Ana, a child of an earlier fork of my own lineage mater, is one of the professors I expected to study with. I believed I would find her teaching in one of the outer republics, but apparently, two years before I arrived at Taj Beacon, she accepted a teaching post here, in Shin-Tethys. While I was in transit, I gather she disappeared. My lineage mater would be angry with me if I left a sib, even a distant one, in trouble without making at least some attempt to find her, so I took the first available passage to come here. Along the way we were waylaid and audited by feral insurance underwriters, who told me that apparently the chapel I had taken a working passage with was engaged in questionable practices and that my sib was suspected by various parties of having been involved in some sort of skullduggery. Now. Can I point out that the record will show that I wasn’t even in this star system when my sister went missing?”

  Serjeant Bull sighed lugubriously. The gill slits in his neck vented slightly as he exhaled: “I believe you. Millions wouldn’t. However, Professor Alizond, there is the matter of your wallet contents. And of your oddly configured second soul. If you wouldn’t mind explaining again?”

  I tried not to roll my eyes. “I am of a modestly wealthy lineage, and I am embarked on a course of travel and study that was expected to take decades of travel time and multiple interstellar transmissions to complete. Don’t you think it would be rash of me to have set off on such a journey without a substantial amount of money on my person, much of it in long-term currency units that could be converted along the way to pay for my later transmission sectors? And as for my highly suspicious second chip, you are aware that my scholarly pilgrimage is a sabbatical activity, and when I am not sitting in a police interview room or traveling between universities, I am a researcher employed by a bank? As such, I am from time to time entrusted with custody of extremely confidential information—material that must be held as closely as my own soul. I should also like to note that banking is a relatively safe occupation: I am not in any significant physical danger from day to day. A single running backup of my soul-state is plenty under those circumstances.”

  “A banker.” He tapped the tabletop, making an annotation in a script I was unable to recognize. “Can you discuss your job? Not any specific confidences, but in general outline?”

  “In general outline? Hmm. Banking, you must understand, is primarily concerned with managing and avoiding risk. Most people think it’s about debt, but debt is merely the starting point. If you wish to borrow money from a banker, the banker will want to know, first and foremost, whether you are likely to repay them. The profit from a loan must be offset against the risk of default or nonpayment: Only by making more loans that repay a profit than loans that end in default can a bank remain in business in the long term, unless it is a currency-issuing bank, in which case . . . but I digress. I do not work in the part of the bank that analyzes the risk posed by individuals. I am a scholar: I research the history of financial frauds, in order that my employers may develop procedures to guard against them. We have inherited a financial system thousands of years old, covering hundreds of star systems. The variety and range of scams and swindles and rackets and cons is endless, and different methods go in and out of fashion.” I managed to summon up a tight-lipped smile: “My job is to invent mechanisms that prevent financial crime.”

  Sergeant Bull tapped the tabletop again. “So you say.” His expression was morose. Three times round the block over two days, and we were back where we’d started. “So you say . . .” He paused. “Let me ask you a hypothetical question. Suppose—this is a question, not a promise—I were to arrange to release you without charge tomorrow, and with a temporary visitor’s visa. What would you do?”

  “Why”—I leaned back in the uncomfortably hard chair I had been provided with—“I’d look for Ana. To the best of my abilities, anyway, to see if she’s left any sign of where she might have gone. Obviously, you and your colleagues have been searching for her for some time, but there’s always a chance that as a sib descended from the same archetype, I might have some insight into her actions. Assuming that her disappearance was voluntary, of course.”

  “And if you found nothing?”

  I had a strong sense that this hypothetical was not very hypothetical at all: “I came to Dojima System to study with her. I can’t move on without being sure that she’s”—the skeuomorphic swallow reflex kicked in: Saying dead was difficult—“before I continue on my pilgrimage. But if she’s disappeared without sign, eventually I’ll have to, have to . . .”

  He nodded. Was that sympathy in his expression? Or just the understanding of a police officer evaluating a suspect and finding her behavior to be consistent with that of a grieving relative rather than a possible perpetrator?

  “I understand,” he said. Then: “I’ll see what I can do.” He rose to leave. “Wait here.”

  I waited. And waited. And then—

  * * *

  Along time ago—2686 years and fifty-three days in sidereal time, not accounting for relativistic effects—the starship Atlantis spread her vast and tenuous sail and her backers switched on the propulsion beams that would boost her up to cruise speed for a four-century flight.

  Atlantis’s destination was a hitherto-unvisited M-class red-dwarf star. Painstaking observation had detected a pair of wet gas giant planets with numerous moons, and at least two debris belts: not a first-rank example of prime real estate but good enough to justify the gamble. Four out of five starships usually survived to make starfall: 80 percent of the colonies they established took root eventually. Atlantis stood a better-than-usual chance of flourishing, for it had barely a parsec to travel, and its target was a compact system with plenty of sunlit asteroids to take root on—a type of system for which the colonization protocols were well understood.
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  Let me walk you through the history of Atlantis colony.

  First, the construction and launch. Seventy years to organize and plan, to train the crew, build the vessel and its launch-support structures. Finally, it spreads its sail, and the giant beam stations in low solar orbit light up, blasting terawatts of power at it. Power that, received, can be focused on the billion tons of water ice and hydrogen slush that the ship carries for reaction mass. The starship accelerates slowly, initially at not much more than a hundredth of a gee; and it gets less power from the beam as the distance from the launch station increases. But it keeps accelerating for years, then decades, lightening as it expends reaction mass and gathering pace as it spirals out of the star system of its birth. After two years, it is speeding outward at stellar-escape velocity. At ten years, nothing from the inner star system stands a chance of catching up with it. When the launch beams shut down a century into the voyage, the starship is most of a light-year from home, racing into the interstellar gulf at three thousand kilometers per second: and it has discarded all but a fiftieth of its launch mass.

  Many hazards can destroy a starship in flight. The environment it flies through is intensely hostile; at 1 percent of light speed, the ship’s momentum effectively turns the cold hydrogen and helium atoms of the interstellar medium into hard radiation. A grain of ice with a mass of milligrams packs the impact energy of tons of high explosive. Other threats can kill a ship in flight: In one memorable incident, a starship flew through the radiation jet of a distant gamma-ray burster: Secondary activation effects reduced its crew to much the same condition as Lady Cybelle.