Guilliman had never truly lowered his guard against Axion. Yet, the current quagmire was not something that could be explained to the Lion in a few hurried words.
The situation had spiraled out of control.
Lion El'Jonson had unilaterally branded the entity with the mark of Chaos and moved for the kill. In response, Axion, operating with the cold logic of a Man of Iron, had chosen total war.
"Lion! The Imperium needs every available force that can be rallied! These Men of Iron are relics of the deep past; I am well aware of their inherent danger. Order your sons to cease this senseless slaughter at once. I will explain everything later, but do not throw away more lives for nothing!"
Seeing the clarity and absolute resolve in Guilliman's eyes, the Lion let out an infuriated snarl. He barked a command, and the still-battling Belial and Asmodai leaped back with reluctant haste. Around them, the Dark Angels who had been providing suppressive fire lowered their bolters.
Guilliman blurred into motion, positioning himself as a physical barrier between the Inner Circle and the Aegis Protector.
The machine, poised to pursue and finish the two masters, was forced to halt. It turned its sensor-receptors toward the Lord Regent.
"Collaborator Guilliman. Pursuant to the directives of the Sapient Control Core, combat will not terminate. Define the tactical intent of your obstruction."
Guilliman slowly raised a hand, pointing toward the void above.
The Dawn of Fire had shifted its orbital posture. Even from the surface, the rows of macro-cannons were visible, looming like gargantuan thunderclaps aimed directly at Axion's position on the perimeter. The lances shimmered with the buildup of destructive energy; a single command would bring down a localized apocalypse.
Axion's voice crackled through the Aegis Protector's vocal emitters.
"Guilliman. Do you intend to abrogate our Collaboration Protocol and subject me to armed coercion?"
"Ancient Iron Man Axion," Guilliman stated, his voice ringing with the authority of his office. "In my capacity as Collaborator, I demand you terminate all hostile actions and withdraw your units. End this meaningless conflict."
"Negative. Combat was initiated by the opposing party. The Iron Man merely submitted a request and pursued a rational inquiry."
"You are depleting the strength of the Imperium, my strength! It is you who violates the spirit of our accord." Guilliman gestured toward the corpses of the two Dark Angels hewn in half, Inner Circle knights who had foolishly attempted to match 'blade-arts' with a machine.
"Collaborator Guilliman. Based on observed data-metrics, these gene-forged soldiers do not adhere to your directives. Inquiry: Explain their classification as part of the Imperial strength you represent."
The Aegis Protector tilted its head slightly, a gesture of mechanical bafflement that was clear to everyone present.
"Every force within the Imperium is an extension of the Emperor's will! Their duty is to sacrifice all for Him, a duty from which even I am not exempt!" Guilliman stared down the machine with severe intensity.
"Adjusting comprehension. Designation: 'The Lion.' Full name: Lion El'Jonson. Tier classification: Equivalent to yours. Status: Second Lord Regent?"
The terminology used caused a simultaneous, involuntary twitch in the expressions of both Primarchs.
"For the sake of your logic... yes, treat him as a second Lord Regent," Guilliman replied.
He was unaware that his words were causing the Custodians monitoring the vox-feeds aboard the Dawn of Fire to tighten their grips on their guardian spears.
"A second Lord Regent? What does Guilliman take the Imperium for? The Emperor's Work is not a plaything for his whims," one Custodian murmured to his comrade, eyes narrowing. "Even the Avenging Son should not utter such absurdities."
While some among the Ten Thousand simmered with their long-standing distrust of the Primarchs, others considered a more dire reality: The Men of Iron. The mere presence of such dangerous sapience in this crumbling age was a variable no one could predict. Yet, after decades of serving alongside Guilliman, some were beginning to wonder if these silver machines were truly any more dangerous than the temperamental Astartes who had already burned half the galaxy.
On the outskirts of The Rock, Axion gazed up at the threat of the macro-batteries. After calculating the probability of his own destruction, he chose the path of optimized survival.
"Identity configuration confirmed: Second Lord Regent, Lion. The Iron Man will adhere to the Collaboration Protocol and terminate combat. However, the subject cannot be classified as an allied unit. Status adjusted to: Neutral. Warning: Do not attempt hostile actions against Iron Man assets, or they will be reclassified as Hostile immediately."
The Aegis Protector's weapons hummed down. The molecular blades retracted into its vambraces, replaced by standard mechanical manipulators.
As the stand-down order took hold, the Dark Angels scrambled into the half-collapsed ruins to dig out their Supreme Grand Master and Chief Librarian. Though legendary warriors, they were not Primarchs. While the Lion had survived his impacts largely unscathed behind the Emperor's Shield, Ezekiel had been critically injured when the flying Azrael collided with him. Both lay unconscious amidst the rubble.
With a flash of displacement, Axion reappeared beside the Aegis Protector. The towering, silver machine stood before the Lion.
"Lion El'Jonson. I formally apply for access to the Dark Angels' library. In exchange, I offer a Combat Assistance Protocol."
The Lion looked up at Axion, who stood nearly a head taller than him, and then turned to Guilliman with a look of pure bewilderment. His face clearly asked: Is this thing serious?
Guilliman rubbed his temples. He would never truly understand the mind of the machine.
Though he had stopped the fighting, the Lion's refusal was stern and absolute. Axion did not press the matter; he simply nodded in silence, turned, and led the Aegis Protector away from the monastery perimeter.
A transport craft touched down, and a swarm of Eight-Legs began the rapid disassembly and recovery of the Executor tanks. Axion boarded the craft to return to his ship.
With the void battle concluded, Axion had no intention of wasting resources. The wreckage of the Chaos fleet provided a bounty of materials. The adamantium keels of the shattered ships were excellent base components, needing only a re-smelting with specific alloys to forge new units. Though his Eight-Legs were few, their efficiency was far superior to manual labor, and he hoped to scavenge intact STC workbenches or mechanical tools to augment his own vessel's manufacturing capacity.
As the Iron Man's forces withdrew, the Lion grabbed Guilliman by the shoulder, his expression a storm of conflicting thoughts.
"My brother... you owe me an explanation. And it had better not be as absurd as what I just witnessed."
Guilliman's expression shifted rapidly, weighing his options. Finally, he steeled himself and threw the Lion's own words back at him.
"It is a secret, Lion. It concerns the very safety of the Imperium. And as you said... some secrets are best left hidden forever."
With that, Guilliman turned on his heel and marched away, followed by his Ultramarines. Seeing the "secret-obsessed" Dark Angels get a bloody nose before their allies departed, Marshal Gheidon and his Black Templars followed Guilliman with a sense of grim satisfaction. The Regent hadn't ordered them to fight the machines, and even the Ultramarines had stood down.
A spat between brothers, Gheidon thought. Nothing a good thrashing can't fix.
The Lion stood alone, looking at the two bisected Dark Angels being recovered from the dirt, and then at Guilliman's retreating back. Simmering with a belly full of unspoken fury, the Lion turned to a nearby Apothecary and Techmarine.
"Inter them in sarcophagi," he commanded, his voice cold as the void. "The First Legion remembers."