Long ago, the Traveler arrived in the solar system. It was a mysterious ball like a mechanical moon, and brought the magic of Light to humanity, increasing lifespans and human intelligence. The Traveler terraformed the planets and moons. Humanity entered a Golden Age.

But the Light had an enemy - a Darkness that had tracked it across the universe. When the Darkness fell upon the solar system, the Golden Age ended in chaos and blood. Most of humanity fled in thousands of ships, only to die in the asteroid belt as the Darkness met them.

The Traveler and the Darkness battled, and the Light won - but at great cost. The Traveler was broken, a huge section torn out of it. As the Darkness retreated and the Traveler sank into a comatose state, it released the ghosts.

Millions of tiny robots emerged from the Traveler, each seeking the soul - the spark - of a single human, living or dead. When a ghost found that spark, they bonded to it, resurrecting the human, and granting them powers of the Light. These were the Risen, intended to be protectors of humanity and the Traveler.

But the Risen, for hundreds of years, had other ideas.

The Ghost had wandered for many years after being sent out by the Traveler. Somewhere in the world, lost in time and space, his partner's corpse lay, perhaps now only dust, awaiting the Ghost's resurrection.

But the world was a big place, and Ghost was small. He searched the nuclear zones, where crumbling city streets were paved with bones. He searched the wilds, where nature had buried corpses deep. He searched the sea, where fragments of the dead formed the muck on the sea floor.

He fled the bloody Warlords, Risen who had seized power for themselves, instead of being protectors. He saw other Risen become the Iron Lords, battling the Warlords and restoring a semblance of civilization. They gathered humanity beneath the sleeping Traveler, where a little Light still trickled from it, empowering and enriching. They began building what they called the Last City.

He watched Risen called the Pilgrim Guard protect wayfarers and guide people to the growing City.

He saw the Pilgrim Guard become the Guardians, and witnessed the organization of the Vanguard, sworn to protect, and not conquer.

In all those centuries, he had not found his own Risen - his Guardian.

It was not in the nature of a Ghost to despair. His mission was to find his Guardian, and he would find his Guardian. But loneliness grew in his core.

He engineered basic clothing, iterating on the design, improving it until he was sure his Risen would be warm and comfortable. He practiced the speech he would make as his Risen's eyes opened and they drew their first breath.

Far out in the Himalayas, Ghost was flying through a snowy mountain pass, bound for the ruins of a monastery, when a spark called to his Light.

The spark of his Risen! Ghost homed in on it, hope replacing his dreary loneliness. It was a tiny thing, remote, yet defying the ages, singing to him of love and courage, friendship and hope. The search led him to the foot of a cliff, where the snow and vegetation had long ago rendered a corpse to dust. Ghost opened his shell and expanded into a sphere of Light, collecting the local quanta and reassembling them into a human body. This was a sacred task, granted by the Traveler to the Ghosts. Ghost performed the task flawlessly, excitement brightening his Light. At last, his loneliness was ended. At last, he had found his best friend.

He built the body of a young man around the spark and added the clothing he had developed for so long. Then Ghost called him back to consciousness.

His Guardian gasped and sat up in the snow, looking around in a daze. He was quite a young man, barely out of his teens, with the medium brown skin of people who had lived here an age ago. "What happened?" he asked. "Who are you?"

"I'm your ghost! You are the Traveler's Chosen, resurrected in the Light."

The young man blinked at him. "Could you maybe ... explain better? What's a Traveler?"

Ghost explained. And explained. The new Guardian listened in growing astonishment. He had died before the Golden Age, long ago in Earth's past.

Finally Ghost wound down. "Do you remember your name?"

"Jayesh," the young man said faintly. "But I don't remember anything else. It's too far away."

"Would you like to name me?" Ghost ventured.

Jayesh studied him, venturing to touch the ghost's star-shaped shell. "I barely know you, Ghost. How can I name someone I barely know?"

"Fair enough," Ghost replied. "I've been Ghost for a thousand years. I suppose a little longer won't hurt."

Jayesh stood up, shivering, despite the clothing Ghost had made for him. "It's so cold. Where are we?"

"The mountains of Tibet," Ghost replied. "We can talk more on the way. For now, let's find a way to get you back to the Last City."

When Jayesh first saw the Traveler above the Last City, he was filled with wonder. And questions. So many questions. What was that thing? Where did it come from? What did it do?

Ghost answered some of these questions, but even he didn't know everything. "Just because the Traveler created me doesn't mean it told me about itself."

The Last City was built in a huge circle beneath the Traveler, surrounded by ten-story walls to keep out marauding aliens called the Fallen. Here were skyscrapers, trains, canals, houses, stores, all the trappings of civilization.

Of the six defense towers on the walls around the City's perimeter, only one was still occupied by Guardians and the Vanguard, their numbers diminished by many wars. They welcomed Jayesh with open arms, offering him a home, companionship, and a chance to protect the last remnants of humanity. Jayesh agreed at once. But it didn't satiate his curiosity.

In the Tower, Jayesh met the Speaker - the masked man who claimed to speak for the Traveler. He held a high office in the Vanguard and helped run the City through a governing body called the Consensus. As soon as Jayesh heard about him, he contrived to meet him and peppered him with questions. The Speaker told him much of history and mankind's dealings with the Traveler. Yet he could not tell much of the Traveler, itself. Jayesh grew frustrated.

Finally, the Speaker told him, "You are young, yet, Guardian. Complete your training. Study and listen. You will discover many answers on your own."

Jayesh took the Titan discipline, thinking to take up the mantle of a protector. He trained, physically, mentally, and learned to handle weapons. But his scores were abysmally low. Commander Zavala was not pleased.

"This is a disgrace, Guardian Jayesh," Zavala exclaimed, slamming one first on the huge table in the command room. "I have never had a Titan perform at the fifty-fourth percentile. If I sent you out on patrol, the Fallen would pick you off like a sick antelope."

Jayesh hung his head. He had no excuse - succeeding in running, jumping, and hitting targets seemed less important than reading the Archives all night long. He'd missed several important tests. Also, most Titans were tall, burly types, excelling at hand to hand combat. Jayesh was small and wiry. His classmates steamrolled him time and again.

Ghost said, "He really has tried, sir. Give him more time. He'll toughen up."

Zavala pointed at the little robot. "I think you made a mistake, Ghost. You brought me a defective Guardian. No Titan should be this far behind after three months of training."

"He's not defective!" Ghost exclaimed. "He has the mind of a scholar."

"And the body of a soldier," Zavala snapped. "Now get out there and raise these scores, Jayesh. You will not disgrace this Tower by dying so soon after your rebirth."

Jayesh crept out of the command room, his face burning. He went out in the Tower courtyard and sat on the wall that overlooked the City and the great, moon-like Traveler.

"Could I be defective?" he asked Ghost. "Does that happen?"

"There are rumors," Ghost replied, floating beside him. "But nobody has ever truly proved it. It would mean that I made a mistake when I detected your spark. And I'm certain I didn't. I looked for you for years, Jay. Many, many trips around the sun."

Jayesh studied the distant Traveler, currently flanked on one side by a bank of white clouds. "It's so scarred," he murmured. "The bottom has holes in it. You said it gave its life to save humanity from the Darkness?"

"Yes," Ghost replied sadly, spinning his four star-like segments around his core. "It lives still, but it is blind and deaf. Even us Ghosts cannot speak to it. It would be so useful if we could. I could ask it about you."

"And discover whether I'm a mistake," Jayesh said bitterly. "You know, it's not fair. I've read the Books of Sorrow. We know more about the Darkness than we do the Light."

"Those books hold their own darkness," Ghost said acidly. "Some Guardians have abandoned the Light, lured away by the promises of the Worms."

Jayesh shuddered. The Books of Sorrow were the ancient history of the alien race known as the Hive, servants of the Darkness from ages past. They worshiped the Great Worms, vile monsters of Darkness that inhabited a gas giant called Fundament - until the Hive helped them escape and hunt the Traveler from galaxy to galaxy. Some Guardians had abandoned the Light, hearing the seductive whisper of those Worms, and doused their own Light in Darkness.

Jayesh gazed longingly at the Traveler. "Yet no Guardian has ever sought to commune with the Light as some do the Darkness?"

"No," Ghost said. "That would mean actually entering the Traveler itself, and that is forbidden."

"Oh." Jayesh watched the clouds obscure the lower half of the Traveler, pouring rain on a section of the City. "Why is it forbidden?"

"Nobody knows what's inside," Ghost replied. "It's the source of our Light. If you didn't die from it, then you might accidentally do unspeakable harm to our already damaged protector."

"I wouldn't harm it," Jayesh protested. "I would only seek to understand. And I'm already living thanks to the Light. How would more Light harm me?"

Ghost studied his Guardian, his tiny blue eye scanning back and forth. "You really mean to do it?"

Jayesh shrugged. "I don't know. I couldn't get up there, anyway. I'd get caught."

"Yes," his Ghost agreed. "Let's not speak of this again."

Jayesh didn't speak of it, but he thought about it. He watched transport ships fly overhead, and thought about it. He watched fighter ships hover, and thought about it.

Meanwhile, he tried harder to bring his scores up. He ran miles on the track. He did hundreds of push-ups and sit-ups, and spent hours on the firing range. Slowly his scores improved. But by his next evaluation, he had only reached the seventy-ninth percentile.

Zavala was scary in a good mood. His blue skin and glowing eyes, combined with his height and heavy silver armor, made him the most imposing person in the entire command room. But when he was angry, he was terrifying.

Jayesh stood at attention, sweat dripping down his back, under his armor. Zavala stared at his tablet, teeth clenched, eyebrows lowered. Slowly he raised his head and stared at Jayesh. Those glowing blue eyes burned like lasers.

"Why," Zavala said quietly, "are your scores so abysmally low, Guardian?"

The Tower hushed. The other Guardians and humans who worked there all fell silent, eavesdropping. Zavala was about to go volcanic on a lazy recruit, which was always a good show.

Jayesh inhaled, trying to steady himself. "I've worked very hard, sir. I don't know why I'm not ranking higher."

"You are a Guardian!" Zavala exploded, his voice booming throughout the command room. "Your very flesh is knitted together out of Light! By these reports, you have the physical strength of a middle-aged human and the shooting accuracy of a blind chimpanzee!"

Jayesh gulped. Zavala's rage swept over him in a wave of red. His thoughts cringed away and instead turned to the Traveler. As Zavala continued to rant at him, Jayesh lost himself in lore he had gleaned about the Light and the Darkness, and his growing plan to sneak aboard the Traveler.

He didn't emerge from his happy place until Zavala turned his outrage on Jayesh's Ghost, accusing him of being defective and thereby creating a defective Guardian. Ghost didn't answer, but shrank his segments together a little tighter, as if trying to hide.

Jayesh gently closed his fingers around his Ghost and drew the little robot protectively against his chest, his eye turned inward. "Sir," he said, when Zavala halted for breath, "this is all on me. Please don't blame my Ghost."

"It is all on you," Zavala snarled. "You have thirty days to bring these scores up to the ninetieth percentile, where a Guardian should be. Should you fail, you will leave this Tower and live the rest of your life as a civilian in the City. Perhaps a job as a garbage collector would suit you better."

Jayesh's knees shook as he left the command room. Behind him, Ikora Rey, the Warlock Vanguard, broke the silence by saying, "I think you were a little harsh, Commander."

At least someone disagreed with Zavala's decree. Jayesh rested on the outer wall and gazed longingly at the Traveler. He released Ghost to float beside him.

"Thank you," Ghost murmured.

"Why aren't my scores better?" Jayesh said. "You've watched me train, Ghost. What am I doing wrong?"

"Nothing is wrong," Ghost replied. "But I do wonder about your past."

"My past?"

"I found your remains at the bottom of a cliff. A kilometer-high cliff. Is it possible that the way you died has affected your rebirth?"

Jayesh frowned. Now that Ghost said it, he did have a dim memory of slipping, falling, careening off points of stone that broke him as he fell. He also recalled a shadowy group of people, their faces long forgotten, as they shoved him off.

"I was murdered," he said.

Ghost looked at him quickly. "Murdered?"

"People threw me off that cliff," Jayesh said slowly. "Thinking about it ... my impression is of betrayal. It hurt me that they did it. But it was so long ago, my memories are very faint."

Ghost traced him with a healing beam, as if the idea of his Guardian being murdered upset him and he wanted to do something about it. But Jayesh was healthy now. He sat there, dark hair ruffled by the breeze, gazing at the Traveler.

"I was slain by Darkness," Jayesh murmured. "Raised in Light. But perhaps the taint still clings to me. It's made me weak."

"Impossible," Ghost replied, but he sounded uncertain. "I've never heard of a Guardian whose past life interfered with his present."

"You've also never heard of a Guardian who became a garbage collector," Jayesh replied ruefully. "But I may be the first."