The Thirteenth Prince
Location: Ultramar Sector — Iax
Time: 012.M42, shortly after the Great Rift's opening
Exhaustion.
If one word could define every moment Roboute Guilliman had experienced since awakening from stasis within the Fortress of Hera on Macragge, it would be that.
Not mortal exhaustion — not fatigue of muscle or lack of sleep.
This was a weight embedded in the soul.
A burden like dragging the entire Imperium from the bottom of a gravity well.
When he awoke, the galaxy was burning.
The Imperium he and his brothers had forged during the Great Crusade — flawed yet rational — had become a bloated, decaying colossus of superstition and fear. A corpse-state devouring itself.
And he, the only returned loyal Primarch, was forced to act as both surgeon and crutch.
The Indomitus Crusade had nearly broken him.
On Holy Terra, within the Throne Room of the Imperial Palace, he had stood before the Golden Throne.
He had felt the presence seated upon it.
His father.
Not as he had once been.
Fragmented. Vast. Inhuman. A godlike psychic storm bound to a dying corpse sustained by the daily sacrifice of a thousand psykers.
Guilliman was Regent of the Imperium.
He was also its loneliest prisoner — bound within the Armor of Fate, bearing a title he had never desired.
Every astropathic transmission was a plea.
Every campaign report, an obituary.
And now—
Iax.
Once the jewel of Ultramar. A garden world of order and prosperity.
Now a festering wound, infected by the Plague War.
Guilliman swung the Emperor's Sword in a blazing arc, the relic blade roaring with psychic fire. A bloated plague-beast was cleaved in half, its corrupted fluids flash-evaporated by the holy flame.
There was no satisfaction in it.
The air itself reeked of rot. Even through his armor's filtration systems, decay pressed against him like a living thing.
This was the domain of his fallen brother.
Mortarion.
"Is this your 'order,' Roboute?"
The voice bypassed battlefield noise and spoke directly into his mind — wet, labored, buzzing like flies inside a skull.
Guilliman turned.
Hovering above the ruined landscape was a colossal winged figure.
Mortarion — Daemon Primarch of Nurgle. Lord of Death.
His once-ashen armor of Barbarus was now a rusted, fungus-choked mockery. Vast, tattered wings shed drifting plague spores. In his grip rested the massive scythe Silence.
"Look upon it," Mortarion rasped, spreading his arms as if embracing the corruption. "Cycle. Decay. Rebirth. True inevitability."
"You traded your soul for rot," Guilliman replied, voice cold through the vox grille. "You are no apostle of life. You are a slave to filth."
"I have Father's love!" Mortarion roared, diving.
Silence carved downward in a storm of warp-corrupted force.
The Emperor's Sword met it mid-air.
The shockwave tore the ground apart. Mortal soldiers nearby died instantly, blood bursting from their eyes and mouths. Lesser daemons were obliterated by the collision alone.
Guilliman absorbed the impact — strength beyond Titans straining against him. The Armor of Fate's reactor spiked into overload warnings.
He was powerful.
But he was tired.
The plague known as the Godblight gnawed at him — Nurgle's conceptual infection meant to erode even a Primarch's vitality.
His reactions slowed by fractions of seconds.
In a duel between Primarchs, that was fatal.
"Everything returns to dust," Mortarion hissed. "I have prepared a garden cell for you, brother…"
They separated.
Then collided again.
Golden psychic fire clashed with virulent warp miasma, tearing at reality.
Was this how it would end?
Killed by his brother.
On a corrupted world.
The Imperium left fatherless once more.
No.
He was a son of Terra.
"For Terra! For Humanity!"
He surged forward.
And then—
The world changed.
Not time.
Something greater.
A rule intruded upon the battlefield — unquestionable, absolute.
A tremor erupted from the direction of the mortal defensive lines — a sector already written off as lost on tactical overlays.
Guilliman froze.
He was not Magnus.
But he was still a Primarch.
And he felt it.
A resonance in his gene-forged blood.
A presence he had felt only once before — in the Throne Room of Terra.
But that presence had been fractured.
Agonized.
This—
Was whole.
Radiant.
Like the rising sun.
"What is this…?"
Mortarion reacted first.
And his reaction was terror.
"No… impossible…" Mortarion's voice broke. "He is bound to Terra! A corpse on a throne! He cannot be here!"
A voice echoed across the battlefield.
Not loud.
Yet it pierced kilometers of distance, tore through warp static, and resounded directly in their minds.
"Kneel."
A golden shockwave rolled across the horizon.
Guilliman instinctively raised the Hand of Dominion.
The light passed over him.
It did not burn.
It healed.
Corrosion peeled from his armor. Exhaustion lifted like fog.
But for Mortarion—
It was annihilation.
The Daemon Primarch screamed.
Fungal armor blistered and burned away. Swarming plague flies turned to ash. His warp tether to Nurgle's Garden strained and snapped.
A single word formed in Guilliman's mind:
Anathema.
"A trap! He's here!" Mortarion shrieked.
The Lord of Death did not threaten.
Did not posture.
He fled.
Wings beat in desperate retreat as he tore open a warp rift and vanished.
Silence fell.
Mortarion… had run.
Guilliman stood stunned.
What weapon had done this?
Ancient relic?
Lost archaeotech?
Or—
Father?
"Regent!"
The vox channel flared to life — Shield-Captain Mardova Corquan of the Adeptus Custodes.
Even the Custodian's voice trembled.
"Coordinates 3-7-Alpha. You must witness this. Immediately."
Guilliman did not answer.
He moved.
---
The approach felt endless.
As they advanced, the terrain transformed.
Black plague-mud had become clean, pale sand.
Foul craters now held clear water.
The stench of rot was gone — replaced by crisp air, sharp as after lightning.
No daemons remained.
From Nurgling to Great Unclean One — gone.
Only black ash marked where they had been.
Imperial soldiers knelt in silence.
Not cheering.
Not weeping.
Simply kneeling.
All facing one direction.
Guilliman strode through them, armor servos humming.
And reached the center.
He had imagined possibilities.
Saint Celestine descending in flame.
A relic weapon from the Dark Age of Technology.
A psychic projection from Terra.
Instead—
He saw a girl.
Thin.
Barefoot.
Wearing an oversized Astra Militarum coat, stained with mud and blood.
Bandaged ankles.
Flaxen hair drifting in windless air, shimmering with golden undertones.
Behind her head rotated a jagged-edged halo of condensed psychic light, humming softly.
Two Custodians knelt before her, heads lowered.
Guilliman stopped.
His memory was flawless.
He did not recognize her.
She was not listed among sanctioned psykers.
Not a saint.
Not nobility.
Before the war, she would have been another forgotten refugee in Ultramar's hive outskirts.
And yet—
Within that fragile shell—
Was something that made a Primarch's instincts scream.
She turned.
Her eyes were twin spheres of liquid gold.
No pupils.
Only burning psychic fire.
That gaze.
He had known it.
On Ullanor.
At Nikaea.
During the Great Crusade.
The same terrible resolve — the willingness to sacrifice anything for humanity's survival.
Even sons.
Even self.
Reason rebelled.
Impossible. Father remained bound to the Golden Throne.
This must be warp manipulation. A construct.
But emotion overwhelmed logic.
The girl smiled.
Not the solemn expression of the Emperor he remembered.
Something… warmer.
Almost amused.
Like an old father observing an overburdened son.
She spoke.
The voice layered, vast, resonant.
Yet the words were simple.
"Thirteenth Son… are you well?"
The Emperor's Sword slipped from Guilliman's grasp.
It struck gravel with a metallic clang.
Roboute Guilliman — Primarch of the XIII Legion, Lord Commander of the Imperium — felt ten thousand years of loneliness fracture at those words.
He tried to speak.
To respond as Regent.
To maintain composure.
His throat closed.
The demigod who had carried the Imperium through darkness now felt like a son hearing his father's voice for the first time in millennia.
His massive armored form trembled.
Then slowly—
He knelt.
"…Father?"