Eva Rostova’s words were a death sentence delivered across the void. You’ve turned it on. And it’s taking our world with it. For a moment, the five people standing on the balcony inside the moon’s heart were frozen, each trapped in a private tableau of horror. Cortez and Orlov instinctively tightened their grips on their rifles, as if they could shoot a tidal wave or a gravitational fluctuation. Dr. Thorne’s face, usually alight with scientific glee, had collapsed into a mask of pale, dawning comprehension. The numbers he’d seen as beautiful and theoretical were now translating into global catastrophe.

Colonel Wei was the first to recover, his mind a fortress built of discipline and protocol. He whirled on Amara, his expression grim. “Dr. Castellanos! You were at the center of this. The station responded to you. What did you see? What did you learn?”

Amara staggered back from the railing, her hand pressed to her temple as if to hold the lingering echoes of the data-storm at bay. The connection had shattered, leaving her mind feeling scoured and raw. She looked at Wei, her eyes wide with a terrifying new understanding. “It wasn’t an attack,” she whispered, her voice hoarse. “It was a diagnostic. A system check. When I touched the pillar, I confirmed our presence, our sentience. The station moved from dormant to active standby. This… this was it running its boot-up sequence.”

“A boot-up sequence that’s causing global disasters!” Wei shot back, his voice tight with controlled fury.

“Because the station is a global disaster mitigation system!” Amara countered, the pieces falling into place with dizzying speed. The images, the concepts, the pure data—it was coalescing into a coherent narrative in her mind. “Don’t you see? The moon isn’t just a watchtower. It’s the control mechanism. For millennia, it’s been making micro-adjustments to its own mass, its gravitational pull, its magnetic field, to counteract cosmic threats and maintain a stable environment on Earth.”

Thorne’s head snapped up. “My God… she’s right. The Chicxulub impactor… the Younger Dryas climate shift… the cyclical ice ages… we’ve always assumed they were random cosmic events and natural cycles. But what if they weren’t? What if they were events the station failed to completely prevent, or could only partially mitigate? It would explain the ‘Great Unconformity’ in the geological record, the billion years of missing rock layers. The Earth wasn't stable by chance. It was kept stable.”

“It’s a gardener,” Amara said, her gaze sweeping the vast chamber, seeing it now not as a machine, but as a tool. “The Obsidians saw life on Earth as a unique, precious experiment. A garden. This station is the environmental control system for that garden. It maintains the temperature, the humidity, the light. It keeps the pests out.”

The implication of her last words hung in the charged air.

“And what happens when the flowers in the garden learn how to climb the fence?” Wei asked, his voice dangerously quiet.

Before Amara could answer, the station provided the answer itself. The light from the central star pulsed once, a single, sharp beat. On the balcony where they stood, the floor began to glow. The same intricate, blue patterns as before flowed out from their feet, but this time they weren't forming star maps. They were coalescing into a focused, holographic display that shimmered into existence in the air before them.

It was a ledger. A history of the station’s function, rendered in the dynamic, geometric language of the Obsidians. Amara, now attuned to its syntax, could read it—not by translating words, but by absorbing the concepts.

The display showed Earth, a vibrant blue sphere. A red, angry line streaked in from the edge of the solar system—a rogue planetoid on a collision course. A beam of focused gravity, impossibly fine and powerful, lanced out from the moon, nudging the planetoid by a fraction of a degree. On the display, its trajectory shifted, showing it missing Earth by a comfortable margin. A date marker appeared next to the event, a complex glyph that Amara’s mind instinctively cross-referenced with the historical data from the antechamber. It corresponded to roughly 75,000 years ago.

Another entry appeared. A massive solar flare, a coronal mass ejection of apocalyptic scale, erupted from the sun. The moon’s magnetic field swelled to a hundred times its normal strength, forming a vast shield that enveloped the Earth, deflecting the storm of charged particles. The date corresponded with a known solar minimum that had baffled astrophysicists for decades.

Entry after entry flowed through the holographic display, a secret history of near-misses and averted apocalypses. The Obsidians weren't just observers; they were custodians. Guardians. They had protected the fragile cradle of life for eons, using technology so advanced it was indistinguishable from the fundamental forces of the universe.

“They saved us,” Orlov murmured, his rifle lowered slightly. “Time and again.”

“They saved the experiment,” Wei corrected, his eyes narrowed. “We were just part of the biomass.”

The ledger’s display sped up, moving into Earth's modern era. It showed the growing chemical haze in the atmosphere, the thinning ozone layer, the rising ocean temperatures. Against each of these trends, the station logged its countermeasures: subtle atmospheric filtering using targeted ionic fields, reinforcement of the magnetosphere, even minute adjustments to ocean currents using focused thermal beams to dissipate heat. It was fighting a losing battle, a thousand small interventions against a species that had become its own extinction event.

Then, the final entries. The Trinity test, which the station registered as an “uncontrolled indigenous fission event.” The launch of Sputnik, labeled “escape from planetary gravity well.” The Apollo landings, flagged as “direct contact with monitoring station.” Each was a trigger, an escalation.

And finally, their own arrival. The display zoomed into Site Alpha, showing the Aethelred landing. It showed Amara touching the pillar. A new, stark glyph flashed into being, a symbol of stark warning. It translated in her mind with chilling clarity: Garden Has Become Self-Aware. Custodian Protocol Activated.

“Custodian Protocol,” Amara breathed. “That’s what this is. We’ve reached a stage of development they were watching for. The point where we could leave our planet and potentially disrupt the experiment ourselves, or draw the attention of others.”

“Others?” Cortez asked, his gaze flicking nervously towards the blackness of the transit corridor. “What others?”

The display answered him. The star-map from the antechamber reappeared, but this time it was different. It showed the other green-glowing points of life in the local cluster. And from several of them, predatory red lines emerged, vectors of expansion and consumption. These lines moved through the star-map, extinguishing other, weaker points of light. They were depictions of other spacefaring civilizations. Aggressive ones.

But every time one of those red lines veered towards Earth, a massive, impenetrable wall of energy, a quarantine field, was shown projecting from the moon, making the solar system appear empty, uninteresting, barren.

The Obsidians weren't just protecting Earth from cosmic accidents. They were hiding it.

“They were keeping the pests out of the garden,” Thorne said, his voice a strained whisper. “Us being the prize-winning roses, I suppose. They knew about other intelligent life. They were protecting us from them.”

“And now we’ve knocked on the door and announced to the entire neighborhood that the garden is open for business,” Wei concluded, the grim logic undeniable. “Our own technological signature—our radio waves, our nuclear detonations—it’s like a beacon. The station was masking it, but by waking it up, we've amplified the signal.”

The final, terrifying piece of the puzzle slotted into place. The Custodian Protocol wasn’t just about assessing humanity. It was about containing the fallout. The increased gravity, the magnetic flux—it wasn't an attack on humanity. It was the station re-calibrating its shielding, reinforcing the fence on a scale humanity couldn’t survive. It was preparing for a threat far greater than a rogue asteroid. It was preparing for a war, and it was willing to sacrifice the garden to protect the cosmic balance of the neighborhood. The planetary chaos was just a side effect of the station reinforcing its armor.

“It’s not trying to kill us,” Amara said, a wave of despair washing over her. “It’s trying to protect the system from us, and from what we might attract. The environmental effects on Earth… they’re incidental. Acceptable losses in its programming. We’re just noise inside the machine as it prepares for its true function.”

From the Odyssey, the frantic voice of the mission commander broke the silence. "Rostova, relay to the surface team! We're detecting a high-energy particle stream on a direct intercept course with the solar system. Origin is the Gliese 876 system. It's moving at near light-speed. It's not a natural phenomenon. It’s a probe. A scout.”

On the holographic display before them, a new red line appeared, streaking towards their solar system from the direction of a star that corresponded to Gliese 876.

The Obsidians' greatest fear had been realized. Something had heard them. Something was coming.

And the station’s response was to lock the gates, flood the garden, and prepare for battle, utterly indifferent to the fate of the fleeting, intelligent life-forms crawling on the surface of the planet it was built to protect. The Obsidians had been custodians of life, but their automated legacy was a custodian of cosmic stability, and humanity was now just a variable in a terrifying equation. The choice was clear: preserve the garden and risk interstellar contamination, or sterilize the garden to maintain the quarantine. The machine had made its choice.