The moment the stasis field shut down, the temperature inside the Vault of Shadow dropped by tens of degrees.
The formidable Custodes guarding the vault instinctively shifted their hands toward their weapons. Even Constantin Valdor narrowed his eyes, his right index finger twitching almost imperceptibly. The sudden arctic plunge brought a sharp, severe discomfort.
Not even the bespoke, astronomical-grade Auramite power armor of the Custodian Guard could completely block the biting chill.
Valdor had seen his share of daemons over the years and had fought through countless desperate campaigns alongside the Emperor. His standing in the Imperium was equivalent to that of the Primarchs or Malcador. Yet, there was one truth he could not help but admit.
The gap in raw power between him and these beings was simply immense—even if the Emperor's trust in him had never wavered because of it.
Still, when confronting a Primarch—especially one who had suffered severe Warp corruption—Valdor knew he lacked the power to single-handedly subdue such a target. That did not stop him from stepping directly in front of the Emperor, using his own armored body to shield his master from the freezing wave, even though he knew the Emperor needed no such protection.
Valdor had witnessed innumerable scenes of corruption and believed he possessed a deep, complete understanding of the word "profane." But looking at the figure before him now, he realized he had still understated the absolute reach of the Warp's ruin.
It was almost unimaginable that this hideous, sanity-draining horror—a monster that triggered instinctual revulsion at a single glance—was once the Second Primarch. The genial, witty, and warm brother whom Horus and the Emperor had both whole-heartedly cherished had been twisted by the Immaterium into this unrecognizable form.
Watching his son slowly stir, the Emperor channeled energy from the depths of the Warp, forcibly suppressing the entity within and plunging the Second back into a deep, dormant slumber.
*Thud, thud, thud...*
Heavy, rhythmic footsteps echoed from behind. Perturabo's towering armored form stepped through the threshold, coming to a halt beside the Emperor.
"You're late."
"I was delayed by administrative business. Your lab or mine?"
"Mine. The facilities are no worse than yours."
Perturabo gave a firm nod. Now that a viable method had been mapped out, today was the day they would bring their second brother back.
---
Inside the golden laboratory, layers of white molecular insulation veiled the surrounding walls, while soft, diffuse lighting illuminated the workspace.
Ranks of stasis chambers stood in immaculate alignment, preserving gene-seed samples harvested across the Great Crusade era alongside priceless bio-tech relics from the Dark Age of Technology.
Surveying the room, Perturabo realized the Emperor had not lied to him over the years. He had indeed abstained from conducting profane, off-the-books genetic trials in secret. Perturabo had privately assumed the Emperor would maintain a few black-budget bio-experiments just in case.
It turned out the Emperor had been surprisingly scrupulous on that front.
Setting aside his golden laurels, the Emperor now wore a simple white robe paired with a pair of dense, tech-heavy optical goggles—looking far more like a dedicated laboratory researcher than an absolute monarch.
Perturabo walked straight to the primary control console. With a sweep of his gauntleted hand, a logic-engine-driven holographic projector deployed from his vambrace, weaving streams of blue data into complex molecular structural diagrams across the air.
"I brought all data on genetic recombination from Olympia," Perturabo said, his fingers flicking rapidly across the array as files exported in rapid succession.
"That includes every reverse-engineering log I ran on Primarch gene-seed over the past eight hundred years. Applying fresh analytical models to the Prime-Blood Vault technology you provided, I've mapped out the Second's exact condition."
Perturabo brought up a side-by-side comparison of a specific gene sequence.
"When you first created us, errors occurred in selective gene expression. That's what introduced the structural distortions into our personalities and distinct Primarch abilities."
"The Second was drafted right after your success with Lion El'Jonson. But the process for Number Two went sideways. Beyond the flaws in selective expression, the Warp used his psychic sensitivity as an entry vector to infiltrate his biology, breaking him down into what he is now."
"Back then, you tried to use raw psychic force to crush the mutated genes inside him. It was like trying to repair a pocket watch with a power hammer—you smashed the gears to a halt, but you didn't fix the underlying mechanism."
The Emperor remained silent for a moment. He walked over to the opposite side of the console and raised a hand, calling up a sequence of glowing golden psychic runes.
Studying the numbers, the Emperor silently conceded the point. Back then, he had been overwhelmed by the momentum of the Great Crusade and the immense logistics of the Webway project, leading him to make a rushed, flawed decision regarding the Second.
He had wanted to save his second son, but the end result proved he lacked the solution at the time. He had resorted to methods as dangerous as direct psychic suppression, only to be forced to seal the Second away inside the Vault of Shadow when all else failed.
"I was overconfident back then," the Emperor murmured softly. "And I made the wrong call."
"Usually you blame everything on Chaos and let Malcador take the fall," Perturabo remarked, glancing at the melancholic Emperor. He was surprised to see him looking so distinctly human in this moment. "What made you admit a mistake today?"
"Does debating it now serve any purpose? Look at where we are."
This was perhaps the most relaxed period the Emperor had enjoyed in millennia. With his sons and generals holding the line on the hardest fronts, he had little left to worry about, spending his days conducting research and refining his mind.
Were the galactic landscape not still so delicate, he would have gladly built a quiet retreat back in Terra's heartlands to live out his days in seclusion.
"Back to the point," the Emperor said, shaking off the thought. "You said you found a working solution. How do we pull Number Two back?"
Perturabo dropped the banter and refocused on the complex genomic matrix. His hands moved fluidly across the interface, weaving blue data streams together with golden psychic runes like a real-time translation between two distinct fundamental languages.
"The Second's mutation exists across three distinct layers. The first layer covers physical geometry, sensory organs, and the nervous system. This layer is the easiest to address: cut off the Warp's psychic feedback loop, perform corrective surgical alignment, and the physical deformities will recede naturally."
"So the first layer is essentially solved?"
"Virtually. The second layer is where the real difficulty lies."
"His genetic framework has undergone a structural mutation that established a symbiotic relationship with his baseline DNA. If we simply sever those mutated strands by force, we might get lucky and pull him back—or we might end up with a puddle of Primarch-grade organic soup."
"What's your solution?"
Perturabo pulled up a new file, projecting a fresh array of biometric data.
"I spent time analyzing Magnus's genetic sequence. His psychic-resistance markers share a high degree of structural similarity with the Second's mutated strands. The core difference is that Magnus's markers function as an active defense mechanism, whereas the Second's function as passive conversion."
"If we swap that passive conversion toggle into an active defense protocol, his body will automatically convert those mutated strands back into normal genetic expressions instead of letting them consume him."
The Emperor studied Perturabo's projected data for a long moment.
"That's structurally unsound. While psychic-resistance markers and mutated strands share high molecular affinity, their expression mechanisms are completely different. You cannot simply substitute one for the other."
"Who said anything about a direct substitution? We edit them directly. Look here."
Perturabo circled a specific segment of the hologram, magnifying a target gene sequence.
"If we replace this promoter region with Magnus's structural variant, the passive conversion turns into conditional conversion. Mutation will only trigger under hyper-specific parameters. Under normal conditions, his DNA will express strictly according to its baseline template."
"In short: the Second's body will only enter a mutated state when subjected to direct, extreme Warp infiltration. Under all standard conditions, he will remain a baseline Primarch."
The Emperor nodded repeatedly in agreement, but a realization suddenly struck him.
"We've locked down the Warp. Even if residual pockets remain, they lack the strength to inflict physical structural corruption in the material universe. Which means you intend for him to—"
"Correct. What we need to do now is consume the Second's Warp essence—or find a way to compress it directly back inside his physical form, forcing a localized daemon-ascension effect. Much like my daemon-ascended brothers, his human physical form can still exist intact."
The bold strategy did not deter the Emperor. Instead, he weighed the practical steps required to execute the trial. With Perturabo, there was never a need to question the core concept—only to determine the logistics of implementation.
"How did you land on this approach?" the Emperor asked, stepping forward to assist Perturabo in forcibly anchoring the Second's Warp essence within the Immaterium.
"I have over 4.4 million sons under my command. Do you think I'd let their gene-seed stay corrupted? In solving their stability, I happened to cross-apply the fix to Number Two."
"Four point four million!?" The Emperor raised an eyebrow, locking eyes with Perturabo. "When did you expand the Legion again?"
"Did you think I was sitting idle like you? Rebuilding the Imperium's infrastructure requires vast numbers of disciplined, mid-level personnel. Astartes are the ultimate builders."
Perturabo's voice was even and matter-of-fact. "When manpower fell short, I manufactured it; when gene-seed proved unstable, I refined it; when surgical procedures were slow, I optimized them; when logistics choked, I redesigned the networks. The Iron Warriors today can match your Custodes in precision and scale—it's only your old habits that keep you stubborn."
The corner of the Emperor's eye twitched slightly. *Why don't you just take the throne yourself, you ambitious rebel?*
"Moving on," the Emperor said aloud, gesturing toward the mutated form resting on the table. "What is the next step?"
"Complete the genetic re-sequencing at the molecular level, then use the edited strands to re-infect his body. His Primarch physiology will accept the modifications naturally because it won't recognize them as an external attack, but as an automated self-repair cycle."
"Like re-writing a corrupted code block into a clean release?"
"Precisely. The difference is that his body won't reject the patch, because the source material originates from his own genetic code. That is the beauty of the Primarch architecture—our bodies are perpetually trying to revert to the original template."
"If you provide a template closer to the original baseline than his current state, his physiology will actively embrace it. You gave us exceptional genetic foundations when you made us."
Perturabo offered the praise sincerely. He was certain that even at the height of the Dark Age of Technology, the bio-engineering behind the Primarch project would have stood at the absolute pinnacle of scientific achievement.
"Those were derived from my genetic sequence and Erda's," the Emperor noted softly. "The peak of perpetual human DNA. Even Malcador was awed by the creation—he actually wanted to craft a few female Primarchs at the time, but I shot the idea down on the spot."
"If Erda hadn't lost her mind and let herself be manipulated by Chaos, you all would have grown up inside the Imperial Palace as master commanders. Things turned out well enough now, but Horus is still lost to us, and we have yet to find a way to recover Eleven."
A shadow of grief crossed the Emperor's face. He still could not forget the loss of Horus—his first-recovered son, his standard-bearer.
Seeing the Emperor slipping into old memories again, Perturabo felt a cold shudder and cut him off immediately, wanting no part of an emotional spiral.
"There is one last detail. It is critical."
"What is it?" The Emperor snapped back to the present.
"While your initial genetic template was powerful, it possessed a fundamental flaw—one I cannot edit out, because it forms our core underlying framework."
"Even you can't alter it?"
"How do you re-code personality? The stubbornness and psychological flaws present in us Primarchs were inherited directly from you two."
Perturabo gestured to his own head. "It's a psychological issue baked directly into the genetic code. I can solve technical errors, but how am I supposed to patch a psychological defect?"
"Should we... bring Angron back in?" the Emperor suggested, thinking of the red-angel who had recently finished his "sentence" and returned to his Chapter.
"No. Angron can only absorb and process raw emotional feedback. At best, he's a biological shock-absorber. He can't fix structural personality flaws."
Perturabo was beginning to realize how vital Horus had truly been; only the Warmaster had possessed the unique charisma required to balance the Primarchs' volatile personalities and smooth over internal friction.
"Forget it. Let's pull Number Two back first," Perturabo concluded. "We can deal with his personality once he's breathing."
The Emperor had no better solution to offer. He had never been a conventional father; having never known a normal childhood himself, he lacked the frame of reference to offer proper parental guidance.
Not every Primarch could grow up like Roboute Guilliman, Corvus Corax, or Perturabo; most had been raised in wildly distorted environments.
---
Focusing his mind, Perturabo engaged his logic-engine, steering nanometer-scale surgical apparatus with absolute precision. Concurrently, the Emperor's psychic power manifested as thousands of fine, golden threads, each anchoring directly to a specific node on the Second Primarch's genomic map.
Proxies of Magnus, Guilliman, and Mortarion—the new occupant of the Golden Throne—manifested inside the room alongside Valdor to observe the procedure. Outside the heavy blast doors, a detachment of Custodes stood guard over an experiment capable of reshaping the Imperium.
The Emperor's psychic threads began slicing away the promoter regions of the mutated genes with microscopic accuracy, instantly inserting the revised genetic sequences into the gaps. Perturabo's logic-engine delivered real-time biometric telemetry, verifying the expression accuracy after every single edit.
Perturabo's hands moved across the interface in a blur, every input timed to the nanosecond. His breathing remained dead level, his heart rate steady, his mind processing calculations at speeds that would have melted a standard Magos's cortex.
For an Archmagos of the Mechanicus, this level of precision work would have been a nightmare scenario, instantly overloading their processors. For Perturabo, it was routine operation—though the fact that the subject was his own brother led him to set aside his usual detached indifference.
When the final genetic fragment slid smoothly into place, Perturabo and the Emperor let out a long, synchronized exhale. The onlookers inside the chamber relaxed unconsciously.
Staring at the silent form resting quietly on the surgical altar, the group felt a brief, surreal sense of dislocation.
Memories that had been restored—yet remained distant and unfamiliar—surged back into their minds.
His face was sharp and stern, carrying a heavy, weathered age that belied his physical youth.
Among the Primarchs, only Angron and Corax shared that specific look, as most of their brothers possessed faces that looked timelessly mature.
Soft, dark-gray hair fell smoothly across the metallic surface of the operating table. His skin carried a healthy, bronze tone, and his muscle structure was clean, powerful, and fluid—devoid of any remaining trace of Warp mutation.
A steady, deep breath began to rise and fall from his chest. Within his torso, the heavy, thunderous beat of two Primarch hearts echoed clearly through the room.
His eyelids fluttered once, then slowly opened. As soft, clean light hit his pupils, he pushed himself up into a sitting position on the table.
His dark brown eyes no longer held the twisted abyss of the Immaterium; they were clear, calm, and slightly bewildered.
His gaze unfocused briefly as his mind fought off the lingering disorientation of an agonizingly long slumber.
He blinked, his pupils focusing on the figures gathered around him. A profound, instinctual familiarity washed over his mind.
"Welcome home, my son," the Emperor said gently.