'What could cause such a thing?'

Fabius shrugged. 'Nothing of this world,' he said with a grin of dreadful appetite. 'It is quite fascinating, you understand. It is as though his form is preparing for some great ascension, a wondrous shedding of a redundant form as his flesh is remade into something extraordinary.'

'And you never thought to mention this?' asked Lucius, still very much aware of the blade at his throat. Just by speaking, he caused its monomolecular tip to pierce his skin.

'It was too soon to speak,' snapped Fabius. 'I do not pause in my observations as you would not pause in the midst of a duel.'

'You mean you believe him?' asked Marius Vairosean, his stretched face unable to hide the revulsion he felt at the thought of their master's body being hijacked by another. Marius had ever been the loyal lapdog of the primarch, unquestioningly following his orders and never once doubting their course.

'I do, Vairosean,' said Fabius. 'My research is unfinished, but I believe that another entity resides within the Phoenician and prepares to transform him into some new image.'

Lucius took grim pleasure in his vindication as the First Captain's knife was removed from his throat. The circling captains paused in their threatening dance, shaken and enthralled that the wild claims of the swordsman had been backed up by no less a figure than Fabius.

Kaesoron lowered him to the deck and released his grip.

Lucius found it grimly amusing that it had been their very loyalty to Fulgrim that had seen them cast as traitors in this rebellion. Blind, unquestioning devotion to one luminous being had been the origin of their damnation in the eyes of the Imperium. The irony was not lost on any of them.

'How long before this transformation occurs?' asked Kaesoron.

Fabius shook his head. 'It is impossible to say for sure, but I would expect this pupating stage of development to be rapid. Indeed, the change in physicality might already be under way. It could be too late to stop it.'

'But it might not?' said Lucius.

'Nothing is certain,' admitted Fabius.

'Then we have to try,' stated the First Captain. 'If Fulgrim is no longer master of his own body then we have to get him back. We are his sons, and whatever has claimed his flesh must be captured and cast out of his body. Lord Fulgrim is our gene-father and I take orders from no one but him.'

A charge of febrile excitement swept through the gathered captains, and Lucius let out a shuddering sigh. He had convinced the others of his suspicions while keeping his blood inside his body and his head upon his shoulders.

'So, a pertinent question...' said Lucius. 'How do we go about capturing a primarch?'

10.

The Gallery of Swords was a place where the exhibitionists of the Emperor's Children liked to display their latest flesh masterpieces. Devotees of Apothecary Fabius, hoping to attract his notice, would drape their latest confections of macabre living art from the bull-headed statues that lined the grand processional of the Andronicus.

The towering granite-hewn heroes of the Legion, warriors who had cut the first histories of the Emperor's Children into the meat of the galaxy, were no longer recognisable as human. Their lovingly-carved faces had been recut, defaced and shaped anew into forms pleasing to the lurid aesthetics of the Legion. Leering grotesques kept watch on those who passed beneath them, and all who gazed upon them felt the wondrous horror of their debauched expressions.

Apothecary Fabius made his lair beneath the Gallery of Swords, a sprawling medicae complex that had been transformed from a place of healing, research and excellence into a shadowed labyrinth of excruciation, screams and nightmarish, inhumane experiments.

Fulgrim swept into the Gallery of Swords with Julius Kaesoron at his side, majestic in a long robe of cream fabric, with silver embroidered stitching running along the hems and collar. A sword belt of mirrored discs encircled his waist, the golden hilt of the anathame never far from Fulgrim's hand.

The primarch's white hair was pulled back into a long scalp-lock woven with mother of pearl and held in place by a circlet of golden laurels. His sculpted chest was bare, and the pale skin bore numerous ridges of scar tissue from the last treatments and enhancements worked upon him by Fabius.

Even though Kaesoron was encased in his spiked and flesh-wrapped Terminator armour, Fulgrim still stood head and shoulders above him. Clad in naught but his finery, Fulgrim was still a warrior to be feared.

The primarch stopped beside one statue that had suffered particularly at the hands of the Legion's craftsmen. He smiled up at the graven image of a reptilian bull's head. The warrior's armour had been cut with blessed symbols, and a trio of hollowed out bodies hung from barbed nooses, one from each outstretched arm, and another from its neck.

'Ah, Illios, you would not know yourself now,' said Fulgrim, with wistful nostalgia. 'I remember the day you first drew sword alongside me as we forged the alliance of the eighteen tribes. We were young then, and warriors who knew nothing of the wider world.'

'Do you wish he were here with us now?' asked Kaesoron.

Fulgrim laughed and shook his head. 'No, for I fear I would have to kill him. He was always so unbending, Julius. He was a man with an unbreakable code of honour from the elder days, I do not think he would have appreciated the enlightenments we have received.'

The primarch took a wistful look at the statue of his former blade brother and a strange expression passed over his alabaster features. Kaesoron's eyes were no longer able to perceive the world as they once had, but even he could see the light of dark memory in the primarch's eyes.

'How naive we were, old friend,' mused Fulgrim. 'How blind...'

'My lord?'

'Nothing, Julius,' said Fulgrim, marching towards the end of the gallery.

'How did Lord Commander Illios die?' asked Kaesoron.

'You know the answer to that, Julius. Your introspections on perfection would have required you to memorise the victories of our past.'

'I know, but to hear it from your lips is always a sublime experience.'

'Very well,' smiled Fulgrim. 'Apothecary Fabius will not mind if we are a little late.'

Kaesoron shook his head. 'I am sure he will not.'

'Good. Ah, Illios, it was your temper that saw you killed,' said Fulgrim, his tone warming with recall. 'You were a man of joyous rages and great sorrows. Never good combinations in a warrior, but you were almost great enough to survive your own weaknesses. Mighty he was, Julius, tall and proud, with the triple-bladed Executioner Falchion and the Armour of Chemos. He was unstoppable. A warrior such as he had only one superior, but he held no grudge that I was his better.'

'It was atop the Barchettan Warlord's city-leviathan he fell, was it not?'

'If you know the story so well, why bid me tell it?' snapped Fulgrim, his eyes ablaze.

'Apologies, lord,' said Kaesoron, keeping his head bowed. 'It is a stirring story, and I was caught up in your words.'

'Then you should have kept your mouth shut, Julius,' said Fulgrim. 'You do not interrupt me when I am speaking. Did Eidolon's death teach you nothing?'

'It was instructional,' said Kaesoron.

'When I speak, I am the star around which you orbit,' said Fulgrim, leaning down to fix Kaesoron with his furious gaze. His black eyes were pools of dark oil, ready to ignite with unspeakable rage. Kaesoron knew he had made a terrible error in speaking and that his life now hung in the balance.

'Who but you, my lord, could speak with such passion and force me into a loose tongue?'

'None other,' agreed Fulgrim. 'It is only natural you should be entranced by my words.'

Fulgrim's wrath evaporated and he slapped a powerful hand on Kaesoron's shoulder guard, staggering the First Captain.

'Ah, we are a pair are we not, Julius?' reflected the primarch. 'Reminiscing of past glories when there are fresh foes against which to beat our breast and fresh sensations to be wrung from each breath.'

'Then let us hurry our steps to Apothecary Fabius,' said Kaesoron, gesturing to the shadowed cloisters at the end of the Gallery of Swords.

'Indeed, we must,' said Fulgrim, his voice aquiver with anticipation. 'I wonder what delights he has for me this time.'

'He promises wondrous things,' said Julius Kaesoron.

11.

Lucius watched Fulgrim and Julius Kaesoron draw near the end of the gallery. His breath was coming in short spikes, and he fought to keep his excitement from getting the better of his caution. As thrillingly treasonous as this was, he wanted to live to see another day. Attacking a primarch was, perhaps, a foolish way to go about that, but his heightened senses were alive with the rush of sensation flooding him.

The stone beneath his bare palm was a smorgasbord of textures, rough, smooth, indented and imperfect in its carving. Polished, moon-blush granite, its original surface planed smooth to microscopic tolerances, then hacked apart with gleeful chisels wielded with screaming abandon. He could no longer tell which of the Legion's heroes he sheltered behind, and that lacuna was like a missing tooth.

Lucius fought this newly-birthed obsession down and wrenched his thoughts back to the task at hand with a shuddering breath. To experience every sensation to the limits of endurance was sublime, but it had a nasty habit of diverting a warrior from his true goals. Bad enough that one warrior should be so caught up, but woe betide any world that became the target of the entire Legion's obsession.

He forced his gaze back down the length of the Gallery of Swords, watching as Kaesoron drew Fulgrim deeper into their trap. Vairosean's warriors were hidden in the shadows of the mighty statues, each shrouded with a falsehood and kept silent with implanted neural shriekers that bombarded their cerebral cortex with howling discordia. When the word was given, those shriekers would go silent, depriving the implanted warriors of the blissful howling and driving them to replace it with fresh stimulus. Vairosean had developed the implants on the journey from Prismatica, and, much as Lucius was loath to credit such a plodder with anything of merit, he had to admit the shriekers transformed the Kakophoni into obsessively fanatical killers on the battlefield.

Against the might of a primarch they would need to be.

It seemed inconceivable that Fulgrim could not be aware of their presence, but as Lucius and the Legion had become so caught up in their own self-obsessions, so too had the primarch. Where Lucius's clouds of obsession were heavy and almost impenetrable, he could only imagine what heights of narcissism a luminous being such as Fulgrim might attain.

Lucius glanced to his right, seeing the shadowed opening that led down into the forsaken lair of Apothecary Fabius. He remembered descending into the dimly-lit labyrinth after his defection from the fools on Isstvan III, his every nerve alive with fearful anticipation. He had set foot in the Apothecarion a handful of times only, his skills so great as to rarely require medical attention. He remembered it as a sterile place of clinical, antiseptic chill, but it had become a gallery of grotesqueries, its walls spattered with rust-coloured stains and hung with biological trophies, mutant curios and bubbling tanks of noxious fluids.

The stink had been incredible, but once Fabius had opened him up and remade him in the primarch's image, it had become a place of wonders to him. As much as he revelled in the glorious worlds opened up to him by Fabius, he could never bring himself to like him. He supposed such things were immaterial now.

He heard Fulgrim ask a question, but the words were lost to him, and he swore silently as he realised he had been distracted once more. Taking a grip on himself, Lucius narrowed his concentration to a sharp blade of focus. Fulgrim was almost upon him, and as architect of this plan, it fell to Lucius to make the first move.

Lucius stepped from the shadows, and the fractional space that separated life and death grew ever thinner. His senses surged with the vividness of this moment, the thrilling anticipation of what he was doing, the sheer madness of it and the irreversible nature of this act.

'Lucius?' said Fulgrim with an amused smile. 'What are you doing here?'

'I have come to speak to you.'

'No, "my lord", Lucius? Have you forgotten to whom you speak?'

'I don't know who I'm speaking to,' said Lucius, staring into the hard, opaque orbs of Fulgrim's eyes. He saw no pity, no humanity and nothing that spoke to him of the lord and master he had loved and served with all his heart. He wondered if that was true or if he was just remembering a past that didn't exist, a fictive history invented to justify this moment.

'I am Fulgrim, Master of the Emperor's Children,' said Fulgrim, glancing about himself as though stretching his senses out and gradually becoming aware of the noose into which he had just placed his neck. 'And you will obey me.'

Lucius shook his head and rested his palm on the pommel of his sword. He wasn't surprised to realise it was slick with sweat.

'I don't know what you are, but you are not Fulgrim,' said Lucius, and the primarch laughed. It was a good laugh, infectious and rich with deep amusement. It was the laugh of a man who knows the joke he is hearing should be appreciated on a level beyond that which everyone else around him understands.

Fulgrim grinned, his dark eyes alight with perverse pleasure at the situation.

'You think you can take me, swordsman? Is that it?' asked Fulgrim. 'I see how you look at me, the obsessive study and drive to prove yourself better than everyone else. You think I don't see how you wish you could pit your blade against mine?'

Lucius hid his surprise. He had assumed Fulgrim to be too self-absorbed to notice his calculating scrutiny, but he should have understood that true self-obsession could only be fed by the attentions of others. Fulgrim would have basked in Lucius's study, and who knew what else he had done? Had his every movement been a pantomime to lull Lucius into assuming superiority or was this just a calculated bluff?

'I have watched you ever since Isstvan V, and you are not the same warrior I followed into battle on Laeran. The Fulgrim I followed onto the surface of that eldar world is not the same one looking at me and daring me to come at him. You are an impostor with my master's face and I will take no orders from a usurper.'

Fulgrim laughed once more, squatting down on his haunches as the hilarity of Lucius's words threatened to overcome him. Lucius scowled in petulant irritation. What had he said that was so funny? He glanced at Kaesoron, but it was impossible to read the First Captain's expression.

'Oh, you are a rare and precious treasure, Lucius,' roared Fulgrim. 'Don't you see? We all take our orders from a usurper. Horus Lupercal has not yet earned the title of Emperor. Until then, what else is he but a usurper?'

'That's not the same,' said Lucius, feeling his moral high ground in this confrontation eroding beneath him. 'Horus Lupercal is the Warmaster, but you are not Fulgrim. I see his face, but something else lurks behind it, something spawned by the same powers that granted us the power to fully experience the wonders this galaxy has to offer.'

Fulgrim rose to his full height and said, 'If that were the case, swordsman, should you not then prostrate yourself before me and beg me to open your eyes to fresh wonders? If I am an avatar of the warp's Dark Prince clothed in the flesh of your beloved primarch, am I not doing a better job than he did in showing you how best to sate your hungers and desires?'

Shapes moved in the shadows between the alcoves of statues, and Lucius saw Heliton and Abranxe emerge from the opposite sides of the marble statue of Lord Commander Pelleon. Marius Vairosean marched along the grand processional with his long-necked cannon slung at his side, its dissonance coils thrumming with potential. His Kakophoni emerged from their hiding places, eyes wide with madness and the need to be driven into sonic ecstasy.

Apothecary Fabius stepped from the arched entrance to his subterranean kingdom, flanked by Kalimos, Daimon, Ruen and Krysander.

Fulgrim turned in a slow circle, taking in the measure of the warriors arrayed against him.

Lucius counted perhaps fifty warriors and wished he had fifty more. And then a hundred more beyond that.

The captains of the Legion encircled Fulgrim, each with their weapon unsheathed and with murder in their hearts. Lucius drew his blade and rolled his shoulders to loosen the muscles. They had not come to kill Fulgrim if such a thing was even possible for mortals but this rapidly-unfolding drama had all the hallmarks of a situation spiralling out of control.

'Alas, I am betrayed by those I hold most dear,' said Fulgrim, clutching his hands to his breast as though his heart was broken. 'You all countenance these lies? Can you all truthfully believe I am not your beloved gene-sire, who brought us all back from the brink of extinction and who led us to truths denied us by our once-father?'

Fulgrim's face crumpled and Lucius was not a little unsettled to see a single tear work its way down the marbled flawlessness of the primarch's face.

The primarch turned to Julius Kaesoron with a hurt look of betrayal in his eyes.

'Even you, Julius?' said the Phoenician. 'Then fall, Fulgrim!'

'Take him!' bellowed Julius Kaesoron, and the captains of the Legion stepped away from Fulgrim as Marius Vairosean unleashed a barrage of shrieking reverberations from his cannon. Statues split under the sonic assault, and Lucius felt a delicious frisson throughout his body as the aural blast wave threw him to the flagstones of the gallery.

Fulgrim staggered under the impact, his robes ripped from his body with the tearing power of the shockwave. He dropped to one knee, his wreath of golden laurels shattering into thousands of fragments. Beneath his robes, Fulgrim was naked but for a crimson loincloth and Lucius marvelled at the almost serpentine fluidity of his body. Daimon leapt towards the downed primarch with his grotesque maul swinging down like an executioner's axe.

Fulgrim swayed aside from the blow, letting the barbed head of the weapon bury itself in the stone decking. Splinters exploded from the impact, and before Daimon could retrieve his maul, Fulgrim stepped in and drove the heel of his palm into the captain's face. Daimon had no time to scream before his face was smashed hollow. Even as the warrior fell, Fulgrim swept up the maul in his right fist as Ruen darted forwards and rammed his envenomed blade to the hilt into Fulgrim's side.

The haft of the maul slammed down into Ruen's elbow, shattering the bones of his upper and lower arm. The captain's howl of pain was music to Lucius's ears, as Fulgrim tore the absurdly small blade from his body. Fulgrim kicked Ruen away, sending him spinning across the gallery to slam into a statue with a crack of shattering plate and breaking bone.

Lucius circled Fulgrim, not yet willing to commit to the fight. His blade tingled in his grip, eager to taste such rarefied blood and hungry to draw him into the dance of swords.

'Not yet, my beauty,' he whispered. 'Not when there are others to suffer the worst of the primarch's ire and strength.'

If Ruen's toxins were having any effect on Fulgrim, Lucius couldn't say, but it appeared that the captain of the Twenty-First had been premature in his boasts that his banes could fell any living foe.

The Kakophoni unleashed a roaring series of blasts from their sonic weapons, filling the Gallery of Swords with clashing echoes and reverberating harmonies that drew blood from the ears of all that heard them. Fulgrim shrieked in pleasure as the sound vibrated his flesh and bones with a ferocity that should have killed him thrice over.

Heliton stepped in and drove the spiked fist of his cestus gauntlet into Fulgrim's lower back, a blow that would have shattered the spine of even an armoured Adeptus Astartes. The primarch took the blow and spun on his heel. A jabbing elbow put Heliton on his back, his lower jaw hanging by a thread of glistening sinew and pulped bone. Abranxe screamed to see his boon companion laid low and swept his twin swords for Fulgrim's neck. The primarch deflected one sword with the head of Daimon's maul, as Abranxe spun inside the weapon's reach to slide his second blade across Fulgrim's throat.