Convergent Series

by Larry Niven

  But one did. One golden-skinned red-haired man shouted something, waved his sword in a circle over his head, and followed.

  An ancient glacier had dropped blocks of limestone and granite all over this flat, barren region. The biggest rock in sight was twice the height of a man and wider than it was tall. Vatch ran toward it. He had not yet begun to wonder how he would climb it.

  He moved in a quick unbalanced stumble now, his sword and his medical kit bouncing awkwardly at either side. He had dropped the sword once already, when a blade had sliced into him just under the armpit. The heavy-shouldered warrior had paused to gloat, and Vatch had caught the falling sword in his left hand and jabbed upward. Now he cradled his right arm in his left to keep it from flopping loose.

  He'd reached the rock.

  It was split wide open down the middle.

  The red-haired Amber came on like an exuberant child. Vatch had noticed him early in the battle. He'd fought that way too, laughing and slashing about him with playful enthusiasm. Vatch thought his attitude inappropriate to so serious a matter as war.

  Vatch stepped into the mammoth crack, set his back to one side and his feet to the other, and began to work his way up. Recent wounds opened, and blood flowed down the rock. Vatch went on, concentrating on the placement of his feet, trying not to wonder what would happen if the Amber caught him halfway up.

  The red-haired man arrived, blowing and laughing, and found Vatch high above him. He reached up with his sword. Vatch, braced awkwardly between two lips of granite, felt the sharp tip poking him in the small of the back. The Amber was standing on tiptoe; he could reach no further.

  The top was flat. Vatch rolled over on his belly and rested. The world whirled around him. He had lost much blood.

  And he couldn't afford this. He forced himself to sit up and look around. Where was the enemy?

  A rock whizzed past his head. A voice bellowed, "Rammer! Give my regards to the nightwalkers!"

  Vatch heard running footsteps, fading. He stood up.

  Omicron 2 Eridani was a wide, distorted red blob on the flat horizon. Vatch could see far across Mispec Moor. He found his erstwhile enemy jogging north. Far ahead of him swarmed the army of the Ambers.

  Above them, the helicopters were bright motes.

  Vatch smiled and dropped back to prone position. He was safe. No man, woman or child of Sereda would stay at night upon Mispec Moor.

  On Sereda war is a heavily supervised institution. Battles are fought with agreed-upon weaponry.

  Strategy lies in getting the enemy to agree to the right weapons. This day the Greys had been out-strategied. The Ambers had the better swordsmen.

  Seredan war set no limits to the use of medicine, provided that nothing in a medical kit could be used as a weapon, and provided that all medicines must be carried by fighting men. The convention was advantageous to an outworld mercenary.

  Vatch fumbled the medical kit open, one-handed. He suspected that the gathering darkness was partly in his own eyes. But the Spectrum Cure was there: a soft plastic bottle, half-liter size, with a spray hypo and a pistol grip attached. Vatch pressure-injected himself, put the bottle carefully away and let himself roll over on his back.

  The first effect was a tingling all through him.

  Then his wounds stopped bleeding.

  Then they closed.

  His fatigue began to recede.

  Vatch smiled up at the darkening sky. He'd be paid high for this day's work. His sword arm wasn't very good; he'd thought that Sereda's lower gravity would make a mighty warrior of him, but that hadn't worked out. But this Spectrum Cure was tremendous stuff! The biochemists of Miramon Lluagor had formulated it. It was ten years old there, and brand new on Sereda, and the other worlds of the Ushy circuit probably hadn't even heard of it yet. At the start of the battle he'd had enough to inject forty men, to heal them of any wound or disease, as long as their hearts still beat to distribute the stuff. The bottle was two-thirds empty now. He'd done a fair day's work, turning casualties back into fighting men while the battle raged about him.

  The only adverse effect of Spectrum Cure began to show itself. Hunger. His belly was a yawning pit.

  Healing took metabolic energy. Tomas Vatch sat up convulsively and looked about him.

  The damp air of Sereda was turning to mist around the foot of the rock.

  He let himself over the lip, hung by his fingertips, and dropped. His belly was making grinding noises and sending signals of desperation. He had not caten since early this morning. He set off at a brisk walk toward the nearest possible source of dinner: the battleground.

  Twilight was fading rapidly. The mist crept over the ground like a soggy blanket. There were patches of grass— green on the yellow dirt, far apart, each several feet across and sharply bordered, each with a high yellow-tipped stalk springing from the center. The mist covered these too. Soon Vatch could see only a few blossoms like frilly yellow morels hovering at waist level, and shadowy white boulders looming like ghosts around him. His passage set up swirling currents.

  Like most of the rammers, the men who travel the worlds of the Ushy circuit, Vatch had read the fantasies of James Branch Cabell. The early interstellar scout who discovered these worlds four hundred years ago had read Cabell. Toupan, Miramon Lluagor, Sereda, Horvendile, Koschei: the powerful though mortal Ushy of Cabell's fantasies had become five worlds circling five suns in a bent ring, with Earth and Sol making a sixth. Those who settled the Ushy worlds had followed tradition in the naming of names. A man who had read Cabell could guess the nature of a place from its name alone.

  The Mispec Moor of Cabell's writings had been a place of supernatural mystery, a place where reality was vague and higher realities showed through.

  Mispec Moor on Sereda had just that vague look, with darkness falling over waist-high mist and shadowy boulders looming. above; and Vatch now remembered that this Mispec Moor had a complimentary set of legends. Sereda's people did not call them vampires or ghouls, but the fearsome nightwalkers of Mispec Moor seemed a combination of the two legends: things that had been men, whose bite would turn living or dead alike into more nightwalkers. They could survive ordinary weapons, but a silver bullet would stop them, especially if it had been dumdummed by a cross cut into its nose.

  Naturally Tomas Vatch carried no silver bullets and no gun. He was lucky to be carrying a flashlight. He had not expected to be out at night, but the flashlight was part of his kit. He had often needed light to perform his secondary battlefield duties.

  As he neared the place of the fallen soldiers he thought he saw motion in the mist. He raised the flashlight high over his head and drew his sword.

  Thin shapes scampered away from the light. Tombs jumped violently— and then he recognized lopers, the doglike scavengers of Sereda. He kept his sword in hand. The lopers kept their distance, and he let them be. They were here for the same reason he was, he thought with no amusement at all.

  Some soldiers carried bread or rolls of hard candy into battle.

  Some of these never ate their provisions.

  It was a repugnant task, this searching of dead men. He found the body of Robroy Tanner, who had come with him to Sereda aboard a Lluagorian ramship; and he cried, out here where nobody could see him. But he continued to search. He was savagely hungry.

  The lopers had been at some of the bodies. More than once he was tempted to end his whimsical truce.

  The lopers still moved at the periphery of his vision. They seemed shy of the light, but would that last?

  Certainly the legends pointed to something dangerous on Mispec Moor. Could the lopers themselves be subject to something like rabies?

  He found hard candy, and he found two canteens, both nearly empty. He sucked the candy a roll at a time, his cheeks puffed out like a squirrel's. Presently he found the slashed corpse of a man he had eaten breakfast with. Jackpot. He had watched Erwin Mudd take a block of stew from a freezer and double-wrap it in plastic bags, just before they ente
red the battlefield.

  The stew was there. Vatch ate it as it was, cold, and was grateful for it.

  Motion in the mist made him look up.

  Two shadows were coming toward him. They were much bigger than lopers... and man-shaped.

  Vatch stood up and called, "Hello?"

  They came on, taking shape as they neared. A third blurred shadow congealed behind them. They had not answered. Annoyed, Vatch swung the flashlight beam toward them.

  The light caught them full. Vatch held it steady, staring, not believing. Then, still not believing, he screamed and ran.

  ***

  There is a way a healthy man can pace himself so that he can jog for hours across flat land, especially on a low-gravity world like Sereda. Tomis Vatch had that skill.

  But now he ran like a mad sprinter, in sheer panic, his chest heaving, his legs burning. It was a minute or so before he thought to turn off the flashlight so that the things could not follow its glow. It was much longer before he could work up the courage to look back.

  One of the things was following him.

  He did not think to stand and fight. He had seen it too clearly. It was a corpse, weeks dead. He thought of turning toward the city, but,the city was a good distance away; and now he remembered that they locked the gates at night. The first time he had seen them do that, he had asked why, and a native policeman had told him of the nightwalkers. He had had to hear the story from other sources before he knew that he was not being played for a gullible outworlder.

  So he did not turn toward the city. He turned toward the rock that had been his refuge once before.

  The thing followed. It moved at a fast walk; but, where Tomas Vatch had to stop and rest with his hands on his knees to catch his breath before he ran on, the nightwalker never stopped at all. It was a distant shadow when he reached the rock; but his haste was such that he skinned his shoulders working himself up the crack.

  The top of the rock was still warm from daylight. Vatch lay on his back and felt the joy of breathing. The stars were clear and bright above him. There was no sound at all.

  But when his breathing quieted he heard heavy, uneven footsteps.

  He looked over the edge of the rock.

  The nightwalker came wading through the mist in a wobbling shuffle. It walked like it would fall down at every step, and its feet fell joltingly hard. Yet it came fast. Its bulging eyes stared back into Vatch's flashlight.

  Why should a nightwalker care if it sprained its ankles at every step? It was dead, dead and bloated.

  It still wore a soldier's kilt in green plaid, the sign of a commercial war now two weeks old. Above the broad belt a slashed belly wound gaped wide.

  Vatch examined the corpse with self-conscious care. The only way he knew to quell his panic was to put his mind to work. He searched for evidence that this nightwalker was not what it seemed, that it was something else, a native life form, say, with a gift for mimickry.

  It stood at the base of the rock, looking up with dull eyes and slack mouth. A walking dead man.

  There was more motion in the mist... and two lopers came lurching up to stand near the nightwalker.

  When Vatch threw the light on them they stared back unblinking. Presently Vatch realized why. They, too, were dead.

  The policeman had told him that too: that nightwalkers could take the form of lopers and other things.

  He had believed very little of what he had heard... and now he was trying frantically to remember details.

  They were not dangerous in daytime; hadn't he heard that? Then if he could hold out here till morning, he would be safe. He could return to the city.

  But three more man-shapes were coming to join the first.

  And the first was clawing at the side of the rock, trying to find purchase for its fingers. It moved along the base, scraping at the rough side. It entered the crack...

  Three shadows came out of the mist to join their brother. One wore the familiar plaid kilt from that two-week-old battle. One wore a businessman's tunic; its white hair had come away in patches, taking scalp with it. The third had been a small, slender woman, judging from her dress and her long yellow hair.

  They clawed at the rock. They began to spread out along the base.

  And Vatch backed away from the edge and sat down.

  What the hell was this? Legends like this had been left behind on Earth! Dead men did not walk, not without help. Ordinarily they just lay there. What was different about Sereda? What kind of biology could fit? Vatch shook his head violently. The question was nonsense. This was fantasy, and he was in it.

  Yet his mind clutched for explanations:

  Costumes? Suppose a group of Seredans had something to hide out here. (What?) A guard of four in dreadful costumes might hold off a whole city, once the legend of the nightwalker was established (But the legend was a century old. Never mind, the legend could have come first.) Anyone who came close enough to see the fraud could quietly disappear. (Costume and makeup? That gaping putrescent belly wound!)

  Out of the crack in the rock came a fantasy arm, the bone showing through the forearm, the first joints missing on all the ragged fingers. Vatch froze. (Costume?) The other arm came up, and then a dead slack face. The smell reached him...

  Vatch unfroze very suddenly, snatched up his sword and struck overhand. He split the skull to the chin.

  The nightwalker was still trying to pull itself up.

  Vatch struck at the arms. He severed one elbow, then the other, and the nightwalker dropped away without a cry.

  Vatch began to shudder. He couldn't stop the spasms; he could only wait until they passed. He was beginning to understand how the fantasy would end. When the horror became too great, when he could stand it no longer, he would leap screaming to the ground and try to kill them all... And his sword would not be enough.

  It was real! The dead forearms lay near his feet!

  Fantasy!

  Real!

  Wait, wait. A fantasy was something that categorically could not happen. It was always a story, always something that originated in a man's mind. Could he be starring in somebody's fantasy?

  This, a form of entertainment? Then it had holovision beat hands down. But Vatch knew of no world that had the technology to create such a total-experience entertainment, complete with what had to be ersatz memories! No world had that, let alone backward Sereda!

  Wait. Was he really on Sereda? Was the date really 2731? Or was he living through some kind of Gothic historical?

  Was he even Tombs Vatch the rammer? Rammer was a high-prestige career. Someone might well have paid for the illusion that hewas a rammer... and if he had, someone had gotten more than he had bargained for. They'd pull him out of his total-environment cubical or theater in total catatonic withdrawal, if Tomas Vatch didn't get a grip on himself.

  Wait. Was that motion in the mist, off toward the battlefield?

  Or more of his runaway imagination? But no, the mist was a curdling, swirling line, aimed at his rock.

  That almost did it. He almost leapt from the rock and ran. If the city gates were closed he'd run right up the walls... But he waited. In a minute he'd know for sure, one way or another.

  Within the crack the one he had struck sat slumped with its head bowed, disconsolate or truly dead. The other three seemed to be accomplishing very little.

  The dead men from the battlefield streamed toward Vatch's place of refuge. They wore kilts of grey and amber. Less than a hundred of them, casualties in a war between two medium-sized companies, a war which would not have been fought at all if the cost could not be partly defrayed by holovision rights.

  When they came close Vatch began to recognize individuals. There was Erwin Mudd, whose stew he had stolen. There was Roy Tanner the Lluagorian, the rarnmer, the medic. Death cancels all friendships.

  There— Enough. Forget about costumes, Tomas.

  Enough, and too late. The nightwalkers swarmed around the rock and began trying to climb. Vatch s
tood above the crack, sword ready. The sword was all he had.

  Hands came over the edge. He struck at them.

  He looked, around in time to see more hands coming up everywhere along the perimeter. He yelled and circled madly, striking, striking. They were not climbing the rock itself; they were climbing over each other to reach the top. And his sword, its edge dulled by repeated blows against rock and bone, was turning into a club...

  Suddenly he stopped.

  Fantasy? Real? What kind of biology...?

  He spilled his medical kit open and snatched at the bottle of Spectrum Cure. More than his life was at stake here. He was trying to save his sanity.

  The pistol grip fitted his hand neatly. A nightwalker pulled itself over the edge and tottered toward him and he sprayed Spectrum Cure between its eyes. An eroded face appeared near his feet; he sprayed Spectrum Cure into its mouth. Then he stepped back and watched.

  The first one dropped like a sack. The second let go and disappeared from view.

  Nightwalkers were coming up all around him. Vatch moved among them in calm haste, spraying life into them, and they stopped moving. In his mind he gloated. It should have worked, and it had.

  For if anything in this experience was real, then it had to be caused by the biology of Sereda. So: something could infect the dead, to make them move. Bacterium? Fungus? Virus? Whatever it was, it had to have evolved by using dead lopers and other native life forms to spread itself.

  It would walk the infected corpse until there was no sugar or oxygen left in the blood or muscle tissues of the host. That alone could carry the disease further than it could travel by itself. And if it found another host to infect along the way, well and good.

  But the first step in infection would be to restart the heart. It had to be, or the bacterium couldn't spread throughout the host.

  And if the heart was going—

  The Spectrum Cure seemed to be healing them right up. He'd cured about eight of them. They lay at the base of the rock and did not move. Other nightwalkers clustered around them. For the moment they had given up on Vatch's rock.