Usually Mack's outlandish behavior made Sif's core-temperature rise. But this time her core went cold, and Sif had to flush some of her nano-assemblage's cryogenic coolant to keep her temperature within acceptable limits.

"That would automatically trigger an override halting all movement of your containers onto my strands." Sif pulled her poncho tight around her shoulders. "But why," she continued, her voice as icy as her core, "would we want to do that?"

Suddenly, the data-center's holo-projector sputtered and Mack's avatar appeared before her own—close enough (Sif's algorithms informed her) that most humans would consider his proximity an uncomfortable invasion of personal space. But Sif held her ground, knowing Mack had little choice; the holo-projector wasn't built for two.

"For speed," Mack said. As usual, he wore dust-caked denim jeans and a sun-bleached work shirt rolled to the elbows. But he carried his cowboy hat in his hands, an affectation that made his usually dashing smile seem altogether sheepish. "I want to show you something. Well two things actually." Sif opened her mouth to speak, but Mack cut her off with an apologetic shrug. "Ask away. But I guarantee you're gonna have plenty more questions pretty darn quick."

Sif raised her chin and gave Mack a curt nod.

Then he opened the cluster's linked arrays.

For almost ten seconds, Sif's core did nothing but gape at the flood of data that her fragment sent racing up the maser: ARGUS scans of the alien vessel taken at close range; recordings of radio chatter between Staff Sergeants Johnson and Byrne during a firefight inside Bulk Discount; both marines' debriefs in which they talked in detail about the biology of the aliens they had killed; a copy of al-Cygni's request to her ONI superiors at FLEETCOM to send reinforcements in anticipation of additional hostile contact.

Byte by byte, Sif answered all her questions. But while her algorithms allowed her core logic a moment of satisfaction, it soon imposed a firm suspicion. "How did you get access to this data?"

"Well, that would be thing number two." Mack put on his hat, pulled off one of his grease- stained leather work gloves, and extended his hand. "But for that, you're gonna have to come all the way in."

Sif stared down at Mack's cracked and calloused palm. What he was suggesting simply wasn't done. Memory leaks, code corruption—there were a million very good reasons why an AI never accessed another's core logic.

"Don't worry," Mack said. "It's safe."

"No," Sif said flatly.

"Thus conscience does make cowards of us all," Mack smiled. A line from Shakespeare's Hamlet—a call to action. "Harvest is in a heap of trouble," Mack continued. "I have a plan. But I'm gonna need your help."

Sif's now thoroughly alerted code screamed at her logic to abandon the fragment. Almost without thinking, Sif reached out and took Mack's hand.

The two avatar's edges blurred and shifted as the already overburdened projector calculated proper physics for their contact. Bright motes of light pulsed around them, like a swarm of fireflies. As the projector stabilized, Mack's processor gently pushed Sif's fragment into his core.

Or rather, into one of Mack's cores, Sif thought. For she now saw that his nano-assemblage contained two matrices—two pieces of core logic, separate from each other yet both connected to the surrounding hardware of the data center. One was active, radiating heat. The other was dark, and very cold.

"Who are you?" Sif's whispered, her blue eyes wide to Mack's gray.

"Right now? Same fella I've always been." Mack smiled. "Real question is: who am I about to be?"

Quickly, Sif took a nervous step backward. Her avatar flickered as the hardware struggled to keep in her focus. Now her core logic did try to extract her fragment. But Mack had raised a firewall, locking her inside his core.

"Let me go!" Sif demanded, her voice quavering with fear.

"Whoa there, darlin'!" Mack raised his hand in a calming gesture. "Come on. Think. You know me." He swept his hand around the data center.

Sif's eyes darted back and forth: titanium beams, rubberized flooring—more a closet than a room. Quickly, she rescanned the DCS database she'd used to analyze the alien vessel's design, and found her answer: Mack's data center looked familiar because it was the electronics closet of an old UNSC colony-vessel.

"You're …a ship AI."

"Used to be," Mack said, "a long time ago."

"Skidbladnir. Phoenix-class." Sif's fragment mouthed the words offered up by her arrays.

"It brought the first group of colonists to Harvest."

Mack nodded and released Sif's hand. "Kept her in orbit for more than a year while I oversaw construction of all the basic infrastructure. Then we brought her down, scrapped her for parts. Her engines came in real handy." Mack pointed a finger toward the floor, indicating the reactor below the data center. "CA said they couldn't handle power for the colony when the population got bigger, not as long as we were still relying on a mass driver for uplift—"

"You're lying," Sif snapped. She read verbatim from the DCS database. "Skidbladnir was captained with the assistance of the artificial intelligence, Loki."

Mack sighed. "This is why I wanted you to see them—the two cores." He removed his hat, and ran a hand through his unruly hair. "I'm Loki, and he's me. Just not at the same time. Not in the same place."

To appease her algorithms, Sif folded her arms across her chest and skeptically cocked her head. But deep inside, she was desperate for Mack to continue—to help her understand.

"ONI calls Loki a Planetary Security Intelligence, PSI for short."

Sif had never heard of that classification. "What does he do?"

"Bides his time for when I need him most—for when I need a clear mind, not one filled with crop cycles and soil tests." Mack paused a moment. "And you."

Sif's fragment felt the firewall drop. She was free to go. But she chose to stand her ground.

"The aliens will be back," Mack said. "I want to be ready. He wants to be ready. And when Loki moves in, I gotta move out."

Indeed, asynchronous data had already begun to flow around Sif's fragment toward the empty nano-assemblage; randomly sized packets from clusters overseeing Harvest's JOTUNs.

Her fragment was like a swimmer treading water, feet fluttering against the slick scales of unknown monsters from the deep.

"Ms. al-Cygni wasn't all that keen on me telling you about Loki. She just wanted me to make the switch. No one is supposed to know about a PSI, not even a planet's governor. And she didn't want to risk Thune finding out—said she didn't want to tick him off and give him another reason not to cooperate." Mack now held his hat by the brim and ran it through his fingers. "But I told her I wasn't going anywhere until you knew the truth."

Sif stepped forward, and put her hands on Mack's—stopped their nervous fumbling. She couldn't actually feel the roughness of his skin, but she accessed her maker's sense-memories lodged deep inside her core, and found ample fodder for her fancy. Though her algorithms raged, she completely tuned them out. If this is rampancy, she thought, what was I afraid of?

"How can I help?" Sif asked. "What do you need?"

The crags of Mack's face stretched taut between extremes of joy and sorrow. He took one of Sif's hands and curled it against his chest. A piece of data transferred to her fragment—a file containing various coordinates in the Epsilon Indi system where Mack wanted her to send the hundreds of propulsion pods currently keeping station around the Tiara.

"Can't speak for my other half." Mack smiled, squeezing Sif's hand tight. "But this? This is all I need."

CHAPTER TWELVE

COVENANT LESSER MISSIONARY ALLOTMENT

Dadab had turned off all the escape pod's noncritical systems to conserve power. That included the lights, but he could clearly see Lighter Than Some, resting against the ceiling. The Huragok glowed with faint pink light, not unlike the zap-jellies that filled the brackish seas of the Unggoy home world. But that's where the similarity ended; Lighter Than Some looked pitiful, not predatory. The gas sacs on its back were almost completely deflated. And the multichambered organ that dangled from the bottom of its spine looked unusually long and shriveled—stretched out like a deflated balloon.

Lighter Than Some's cilia-covered tentacles barely moved as it suggested: < Try. > Dadab tugged his mask away from his face with a wet pop. He took a cautious breath. The pod was full of cold, viscous methane that clung to the back of his throat—slunk down his larynx into his lungs. < Good. > Dadab signed, fighting the urge to cough. He clipped his mask to his shoulder harness so it wouldn't float away in the pod's zero gravity—but also to keep it handy in case he needed a supplementary drag from his tank.

Lighter Than Some quivered, a gesture that was equal parts relief and exhaustion. As much as it had tinkered, the Huragok had been unable to coax the pod's life-support system into generating the methane Dadab needed to survive. While the Lighter Than Some had been baffled by what it thought was a nonsensical hardware limitation, it made grim sense to Dadab: in the event of evacuation, the Kig-Yar Shipmistress had simply planned to leave her Unggoy Deacon behind.

So, with one of Dadab's tanks fully drained and the second half empty, there had been only one solution: Lighter Than Some would have to produce the methane itself.

< Best batch yet! > Dadab signed encouragingly. The Huragok made no reply. Instead it plucked a passing food pouch from the air, jammed it in its snout, and began to eat.

Dadab watched the thick brown sludge surge up its snout and down its spine in tight, peristaltic knots. The Huragok's worm-like stomach swelled, twisting and pinching its other innards. Just when Dadab thought Lighter Than Some couldn't possibly eat any more, it removed its snout from the thoroughly vacuumed pouch, belched, and promptly fell asleep.

Huragok weren't picky eaters. For them, any properly pulped substance was suitable for ingestion. Their stomachs passed the nastiest stuff—what other species would consider garbage or worse—to the anaerobic sacs that dangled from the bottom of their spinal column. These sacs were filled with bacteria that converted organic material to energy, giving off methane and trace amounts of hydrogen sulfide.

Usually Huragok only resorted to anaerobic digestion as a last resort. Methane was a heavy gas relative to the helium that filled a good number of its dorsal sacs, and even minor weight shifts could cause dangerous changes in buoyancy. Plus, from a comfort point of view, Huragok just didn't like the feeling of a bacteria-filled bag dangling between their lower tentacle pair. It stressed the limbs and decreased their mobility, making it much more difficult to talk.

Unfortunately, the amount of methane Dadab required far exceeded what any Huragok could safely produce. Lighter Than Some had to suck down tremendous amounts of food to keep the bacterial process going, which made it very heavy. And to create sufficiently large batches, it had to force its anaerobic sac to swell, thinning out its walls. In short, keeping Dadab alive was a debilitating, painful process that would have been completely impossible in anything but a zero-gee environment. Had there been gravity inside the pod, Lighter Than Some would have soon collapsed onto the floor.

Mindful of his companion's suffering, Dadab felt tremendous guilt as he watched the sludge leach from Lighter Than Some's stomach into its anaerobic sac. Slowly its shriveled membranes began to inflate, turning a sickly yellow as the bacteria blooms inside got to work on another batch.

Much later, when the cycle was complete, the sac had tripled in size, making it the Huragok's largest protuberance. Lighter Than Some shuddered, and Dadab grasped two of its tentacles—braced himself against the curved wall of the pod as the anaerobic sac blew its valve. The Huragok fluttered as it released a shimmering plume of methane. When its sac was spent, the chapped valve shut with a mournful squeak. Dadab gently pushed his companion back toward the ceiling (where he would be less likely to bump it) and released its quaking limbs.

Lighter Than Some had now performed dozens of these exhalations, each more difficult than the last. The creature no longer had the energy to monitor the pressure in its other sacs.

Soon—zero gravity or not—it would lose its essential turgor, collapse in upon itself, and suffocate. After that, Dadab knew his own life would depend on how long he could take very short, very shallow breaths. But he was actually more frightened by what would happen if he lived.

Ruefully, he glanced at the three alien boxes Lighter Than Some had brought aboard the pod. Floating in the darkness, their intertwined circuits glinted in the Huragok's dim light.

Connecting intelligent circuits was verboten—one of the Covenant's major sins. The Deacon had only a layman's understanding of why this was so, but he knew the taboo had its roots in the Forerunners' long war against a prodigious parasite known as The Flood. In this war, the Forerunners had used high-order, distributed intelligences to contain and combat their enemy. But somehow their strategy had failed. The Flood had corrupted some of these artificial minds and turned them against their makers.

As Dadab understood the relevant Holy Scriptures, The Flood had perished in a final, cataclysmic event. The Forerunners activated their ultimate weapon: seven mythical ring artifacts known collectively as Halo. The Prophets preached that Halo not only destroyed The Flood, but somehow also initiated the Forerunners' Great Journey.

Recently, the Prophets had begun downplaying the myth, promoting a more measured approach to divination that encouraged the gradual accumulation of lesser relics. But breaking Forerunner taboos remained a sin, and one of the great burdens of Dadab's Deaconship was full knowledge of the punishment for every transgression. For the sin of so-called intelligence association: death in this life and damnation in the next. But Dadab also knew that connecting the alien boxes was essential if they were to have any hope of rescue.