The reinforcements answering the call of Horus were great in strength and number. Expeditionary fleets, with elements of the Vlka Fenryka, Imperial Fists, Blood Angels and Thousand Sons legions, led by their primarchs, entered the Nexus system to assist their brother as a unified crusade fleet. Angron of the XIIth World Eaters also answered the call, though far less out of concern like his other brothers and more out of curiosity at what could make the mighty Lupercal beg for aid.

They found the remains of their brother’s fleet keeping to the safety of the largest gas giant, and the captains relayed the dark news that the Luna Wolves were incarcerated on the fourth planet, with Horus among them.

The assembled primarchs reviewed the helmet recordings and battle reports, and they watched in horror as one of their brothers, arguably the greatest amongst them, was brought down by a mere man and his metal abominations while his legionnaires were brutally mutilated. Even Angron’s snarling rage and dark mood was shocked to silence at witnessing the carnage.

Urgent word was sent back to the Emperor of Mankind of this grievous development, and in the meantime, it was Sanguinius who suggested reaching out in an attempt to parley with the Nexus Unity.

“Oh, more of you,” the man known as Sev stated blandly on screens and holograms. He didn’t let the primarchs reply as he continued in a monotone voice. “The primarch Horus is safe, as are the majority of the invading force. You know where they are. If we can get guarantees that you’ll all leave this system alone and in peace, with no further attempts at compromising the Nexus Unity or its territory in any way, I’ll be more than happy to let everyone here go.”

Even as they struggled at the audacity of the Nexus Unity’s ruler, Sev took on a more sinister expression. “Otherwise, I’ll be treating everyone on your end as pests, and that would also mean there are no more prisoners of war, only nuisances to be crushed.”

He finished with a dark smile as he delivered his ultimatum. “Please, for your sake, think this through carefully.”

The composition of the second Imperial diplomatic mission to the Nexus was one that had, until now, never graced any world. Five primarchs were landing onto a world not for battle, but to restart peaceful negotiations. Five primarchs, of which two of them, the Executioner and the Red Angel, were notorious for their lack of diplomatic tact and peaceful intentions.

If not for the grave purpose of the mission, it would have been a feat worthy of propaganda reels. Instead, as they landed on the fourth planet designated as ‘Mars Similis’, the primarchs and their honor guard disembarked from their transports with caution and reluctant humbleness. Even Angron managed to keep a wary calmness as he stomped onto the brown-red planet behind his brothers.

The broken primarch craved violence almost to a suicidal degree, but his senses had not left him so much that he couldn’t understand the significance of Horus being defeated and captured. And there was significance too that all of the invading legionnaires were captured, without a single reported death.

Sanguinius led the delegation, with Magnus and Rogal Dorn just behind him, and Leman Russ and Angron bringing up the rear. The elite guards of each primarch followed after their genesires, betraying their tenseness as they marched with weapons at the ready instead of the parade march a peaceful diplomatic mission would usually entail. The Angel fought back an unnameable discomfort at the back of his head as the delegation met their hosts.

Their opposite party, the leader of the Nexus Unity, stood calmly before them with his greatcoat fluttering lightly in the thin atmosphere. His own honor guard flanked him, men and women in peculiar armor with smooth, ovoid glass helmets that could be mistaken at a glance as a bulkier variant of Eldar armor. Hovering in the air and filling up the plains behind the Nexus humans were their battle automata, metal abominations that took many forms and were the testament to the strength of the Nexus Unity.

Magnus’ quiet voice betrayed his surprise and amazement to his brothers. “These people…their presence is invisible in the Great Ocean.”

Leman Russ gave his cyclopean brother a sideways glance and was clearly raising his eyebrows. “Like Father’s mute sisterhood?”

Still keeping his stoic facade up, the Thousand Sons primarch managed a slight shake of his head. “No, the Sisters of Silence are voids in the Great Ocean, distinct and obvious nothingness. These mortals are invisible, like glass underwater.”

As the primarchs digested the information in their own ways, it was only then that Sanguinius realized the source of his discomfort: his foresight was utterly absent ever since they had entered orbit. There was not even a hint of foreboding at the edges of his senses, no tendrils of premonitions that might suddenly bloom into warnings of the future. Being before the casually assembled mortals of the Nexus brought an unsettling lightness to Sanguinius as his foresight was blinded as if it never existed at all.

Magnus’ own trained sight might make more out of this phenomena, but the Cyclops’ stony silence indicated that the primarch was puzzling over more private discoveries about the Nexus’ humans.

It also occurred to all the primarchs that Sev was somehow breathing, without a helmet or any sign of a breathing aid, in conditions that a normal baseline human would be asphyxiating in. Considering the techsorcery on his end, it wouldn’t be surprising if it was the work of some hidden device or subtle genehancing.

The diplomatic delegation came to a stop several meters from Sev, and Sanguinius shrugged off his unease, offering a slight, formal nod as his wings spread slightly to hopefully hide the snarls and scowls of disdain from Russ and Angron.

“I greet you, Sev of the Nexus. On behalf of the Imperium, and more importantly, my brother primarchs, I, Sanguinius of the Blood Angels, am grateful for the opportunity you have given us for another meeting.”

The grace and warmth of the delivery did little to change Sev’s neutral reaction, and even his guards were unmoved before the raw might radiating from the five primarchs. “I’d say welcome, but I’d be lying,” Sev drawled. There was a commotion, and the legion of automata behind him began to shift and part. The Imperial delegation kept their calm as they saw the procession making its way towards them.

Primarch Horus was leading the somber march, draped in nothing but a simple brown robe. Behind him, his sons were similarly clad, their heads lowered in humiliation as they trod onwards. Despite the parade of prisoners, there was no air of mockery or triumph from Sev or his Nexus soldiers, as if this was not at all a momentous event where mere mortals had bested the genecrafted sons of the Emperor of the Imperium.

The five primarchs looked to their brother, finding Horus hunched a little over and the bright charisma he usually emanated smothered by the ignominy of defeat and capture. Other than that though, he was unharmed, if anything looking somewhat better than before.

“As promised, here is the primarch Horus and his men. Feel free to confirm everyone’s attendance.”

Horus gave a slight, silent nod when the other primarchs glanced meaningfully to him, and then Sanguinius shook his head. “There is no need. We will take your word for it.” None bothered to ask about those from the failed invasion attempt on the Nexus homeworld, those were written off along with the losses from the broken ships orbiting that planet.

The Angel gave a humble nod and bow in reply, again hoping his spread wings would hide the obvious distaste on his brothers’ face. “I thank you for the magnanimity of releasing my brother and his sons.”

“Yeah, I’m sure your rules of war would allow for the same if the roles were reversed,” the Nexus’ leader snarked. A sternness then descended on his features like a dark veil. “As you agreed, every non-living thing on this planet, and those on and around my world will be claimed as spoils of war.” There was an undertone of warning in Sev’s voice, though absent was the haughtiness or arrogance one usually found in victors dictating terms. “Your Imperial fleet will also make no further attempts at landing, orbiting or exploiting any of this system’s celestial bodies and objects. Not unless I have allowed it.”

The Angel gave another nod and bow in reply, but this time his wings couldn’t hide the loud snarl from Angron. The rest of the primarchs froze as the Red Angel stomped forwards, almost frothing at the mouth.

“Little mortal…hnngh…cowering behind his soldiers…”

“Brother, please-” Magnus and Dorn made to hold him back, but Angron shoved them aside, shoved Sanguinius aside as he walked to the forefront and drew his axes.

“Hrr… Come! See how you keep your High Rider arrogance after facing Angron!”

The primarchs and legionnaires froze in surprise, and Sanguinius suddenly regretted not fighting harder to have his brother remain on the fleet.

As the primarchs moved to restrain their brother, Sev waved them back casually, tilting his head to one side even as he took a casual step forward, his automata legion and mortal guards unmoved and unphased. Instead of replying to the challenge, he simply squinted at the forest of wires embedded into the scalp of the Red Angel.

“Are those…implants, or whatever it is…are they self inflicted?” The question had an underlying falseness to it, as if the man already knew the answer. Nonetheless, the query surprised Angron out of his building bloodlust.

“Are they doing the talking for you?” Sev asked the primarch of the World Eaters, and then turned his inquiring gaze upon his stunned brothers behind him.

Before anyone could offer an answer, Angron let out a roar and charged towards Sev with a force that was known to bring down tanks and bastions. He crossed the distance in just a few frenzied steps, and the axes cleaved through the air in brutal arcs. The swings were far from mindless; the paths the axes weaved would have herded the foe into a cruel trap, ending in a ceramite-breaking kick or bisecting slashes. It was a deadly pattern that could rend apart even the most nimble and agile Eldar corsair.

Yet Sev danced aside from the flurry of swings, impossibly overcoming the Red Angel’s superhuman speed to evade every attack and keeping close to the primarch instead of trying to back away. Sanguinius didn’t think any of his brothers could accomplish such a feat, even the master duellists like Lion and Fulgrim would have taken some blows or have wisely conceded the space to attack from a different angle.

But here Sev was easily avoiding the furious rain of axe strikes and somehow remaining untouched, while casually ignoring the growls and roars from the World Eater’s primarch. Primarchs and their honor guards remained frozen in surprise at the man’s unharmed condition.

“Are you done?” Sev mocked, earning a snarl in reply. “Another five strikes then.”

And Sanguinius counted five strikes before the Nexus’ ruler retaliated. Angron’s last moves were a diagonal swing from the right, followed by a horizontal cleave from the left, then a backswing with his right, and then left, and finally a double swing inwards with both axes.

Then Sev was behind Angron, sending a flurry of well-placed punches that broke armor and limbs, sending the World Eater’s primarch to the ground in a heap and roaring with impotent rage. The other primarchs made to intervene at this point, but the Nexus’ ruler raised a hand to stop them. At the same time, the weapons of the Nexus humans and automata rose to the ready.

“Out of charity, I’m going to count this attempt at assault as taking place before our trade was done.” Sev slowly walked over to the fallen primarch, staring particularly at the tangle of wires at the back of Angron’s head.

The primarchs’ enhanced hearing picked up his mutterings. “Huh, percentage damage instead of fixed value.”

And then Sev announced aloud, “I’m claiming this primarch as my prisoner.” Sanguinius and his brothers were about to protest, but Magnus’ gasp made them pause. The primarch of the Blood Angels was about to question his brother, but then he could feel what his brother was no doubt seeing, and the other primarchs no doubt felt the same.

An ethereal wind flowed around Sev, coalescing around Angron. The stink of psychic sorcery or even the well crafted work of Magnus’ powers was absent, but it was still a clearly unnatural phenomena.

The surprise was enough for Sev to reach down towards the grotesque Butcher’s Nails with one hand while another produced a handheld device from his coat. There was a swift yank, and the archeotech implant was separated from its host, dripping blood and brain matter freely from its many invasive tendrils. At the same time the foreign device bathed Angron in a warm white light. The primarch let out a defiant growl that turned into an actual gasp of surprise, a first for any of his brothers to hear.

Against the predictions of the Emperor and expert chirurgeons who had studied Angron’s implants, the World Eaters' primarch was still alive, the gaping wound in the back of his head where the Butcher’s Nails once occupied closing up before Sanguinius’ eyes. Sev deactivated the device in his hand only after naked, pristine skin was left where a forest of wires had once taken root, and stepped back as if to admire his handiwork.

Once more his low mutterings could be heard, though the implications of it still escaped Sanguinius. “Natural rapid regen’s nice… And good sanity recovery too, eh? Wonder if I can copy those…”

Sev then stepped away, turning his back on the primarchs as they and their honor guards attended to the Red Angel. Angron seemed to be in a state of shock, and his features were no longer contorted in depthless rage. “What…what did you do?” came a soft, stunned voice, one that was never heard coming from the broken primarch’s throat before.

Glancing over his shoulder, the ruler of the Nexus lifted the gore-matted Butcher’s Nails in one hand. “Charity work. I’m keeping this, by the way.”