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Warhammer 40K: Fabius Bile – The Primogenitor

7 Minute Read
Oct 26 2021

Warhammer 40K’s Fabius Bile – the Primogenitor. The maddest of scientists, the most twisted and fallen of the noble Astartes Emperor’s Children Apothacarion.

“When a doctor goes wrong, he is the first of criminals. He has nerve. He has knowledge.” ~Terran axiom, M2


Fabius Bile – The Primogenitor

Fabius Bile, originally just Fabius and also known as the Spider and the Primogenitor is a Chaos Space Marine. Prior to the defeat of the Horus Heresy, he was a Lieutenant-Commander and Chief Apothecary of the Emperor’s Children. He is now an infamous mad scientist, specializing in genetic manipulation and the creation of Enhanced Warriors. Unlike most of the Emperor’s Children, Bile does not follow Slaanesh, instead, he devotes himself to science, and research into the creation of Space Marines.


Early Life

Fabius was born to Europan nobility. As a child, he learned the art of fleshcrafting from one of his family’s servants. Among his first experiments was modifying mice to duel each other in elaborate garb and was inconsolable when they disobeyed his orders and killed one another. Shortly after, he was inducted into the III Legion.

Great Crusade

By the end of the Great Crusade, Fabius had risen to Chief Apothecary of the Emperor’s Children and was known for his reclusive and inquisitive nature. As the Heresy and betrayal of the Emperor’s Children loomed, Fabius managed to convince Fulgrim that he could improve upon the Legion’s gene-seed and finalize their quest for perfection. To this end, Fabius began experimenting on both Emperor’s Children and Blood Angels wounded or slain in the War on Murder. This began Fabius’ descent into corruption and madness, as his experiments became ever-more extreme.

Horus Heresy

Once the Heresy began and the Imperium became divided, Fabius was held in high esteem by both Horus and Erebus for his skills in genetic research. Omegon was told by Horus to give Fabius the stolen Data from the Primach project. However the Data Omegon gave Bile was purposefully flawed, so that the traitors would waste manpower and resources, while it would be impossible to gain any benefit from it.

Following the Drop Site Massacre Fabius trawled the ancient choral conclaves on Isstvan V, scavenging knowledge left there by the warsingers of the Isstvan System.


Fabius joined several Emperor’s Children commanders such as Lucius and Marius Vairosean in using extreme torture to exorcise the Daemon that was inhabiting Fulgrim.

At his Primarch’s demand, Fabius produced his first cloned Primarch, creating a replica of Ferrus Manus which Fulgrim tried to again convert to his cause and killing him after he refused. Fabius created multiple clones of Ferrus, all refusing Fulgrim before being killed. Fabius proved vital for the Emperor’s Children during the Heresy, reviving both Eidolon and Lucius at the demand of their Primarch. As the war ground on his experiments became more and more depraved, torturing captive Space Marines of both allied and enemy Legions to give birth to his first generation of Terata.

During the end of the Heresy, Fabius took part in his legion’s attack on Terra, although neither he nor his Legion was actually involved in the siege of the Imperial Palace; instead, they attacked the general population. In the Legion’s unrestrained fervor, millions of Earth’s civilians were murdered. Bile used the opportunity to perform horrific experiments on captives. Human victims were rendered down to create special drugs which heightened the Legionnaires’ feeling of ecstasy.

Long War

In the centuries following the Heresy, he traveled the galaxy offering his services to various planetary lords or rebel leaders, in return for prisoners (the “Flesh-Tithe”) or ancient technical libra. Many of these ambitious overlords came to regret allowing Bile’s experimentation’s on their people, as the results of his atrocities became apparent. His creations have also infiltrated many Imperial planets, helping to hide evidence of his activity and redirect potential enemies. Despite his infamy, Bile still adheres to a twisted version of the old Imperial Truth, believing that only the foolish and weak seek the comfort of gods and seek scientific understanding above all else.

Bile eventually ended up leading a group of affiliated apothecaries from various Legions known as the Consortium based on Urum. Looking for a key to stop the decay of his body and achieve immortality, he was a key participant in the Shattering, the attack by the Emperor’s Children on the Eldar Craftworld Lugganath in 764.M34. . During the attack it became apparent that his former acolyte Oleander Koh and a group of Harlequins engineered the events to try and convince Fabius to lead the Emperor’s Children once more. However, Fabius refused to become a warleader and instead insisted that his work would continue.



For a time, he was tutored in the dark arts of manipulating the flesh in the Tower of Flesh, a Haemonculi stronghold of the Coven of the Thirteen Scars. This eventually led to him tutoring his fellow Emperor’s Children in these dark arts, which led to Bile coming into conflict with the Thirteen Scars at the Battle of Belial IV in 993.M37. The Coven slaughtered those who Bile tutored and surgically ensured that Fabius himself could never speak of what he had learned.

During the Psychic Awakening, Bile stole a precious Death Guard artifact known as the Ark Cornucontagious. This spurred Typhus and his Plague Fleet to pursue the Spider, who was forced to form an alliance with Argento Corian and his Shriven warband. During the subsequent War of the Spider Bile was able to manipulate all sides to his own advantage. The Shriven were modified into hordes of Terata while Corian himself was eventually doomed to become a monstrous golem. During the battle on Bairsten Prime Bile was able to capture a number of Custodes and Sisters of Silence, taking them as test subjects. In the final stage of the war on Dessah Bile was again able to escape as the Shriven, Death Guard, and Custodes destroyed one another. With his research subjects acquired and the Ark Cornucontagious in hand, Bile returned to Urum to begin his work.

Cloning & Rebirth

Due to his original genetic flaw, Bile’s body quickly deteriorates and dies. He has managed to sustain his life over the centuries by creating clones of himself and transferring his own personality and memories into them. The key to Fabius’ cloning process is a neural network that contains regularly updated copies of his neural pathways, these are then normally downloaded into a mindless clone but under emergency circumstances could be transferred into any Transhuman body. The procedure to do this is simple enough for any of his Gland Hounds to complete. Fabius was able to develop the technique by copying Eldar Infinity Circuit technology. This has allowed Fabius has died more times than he can count over the millennia, but each time he is able to return in a new body. Though each new Fabius is in effect a new “person”, they are in essence the same being as they have his exact thoughts, memories, and personality.

Despite this apparent immortality, each of Fabius’ bodies is breaking down faster than the last and he is changing bodies on a regular basis by the 41st Millennia. Moreover, should his neural database be destroyed and not rebuilt, Fabius would not be able to be reborn.

Equipment and Wargear

  • The Chirurgeon– a warp-tainted mechanical device attached to his spine. It pumps demonically charged black ichor around his body giving him unnatural resilience. Spidery limbs tipped with vicious saws, blades and other twisted variations of medical devices extend over his shoulders, which act as both the tools of his experimentation and a means of attack.
  • Rod of Torment– a daemon-forged once belonging to the daemon prince Sh’lacqclak, when it strikes it is able to incapacitate almost any enemy with unbearable pain.
  • Xyclos Needler– a gun that fires virulent poison darts.


In the years following the Heresy, he commanded the Lunar Cruiser Pulchritudinous at the Battle of Harmony. Later his personal vessel was the captured Gladius Frigate Vesalius. He also commands the custom gunship Butcher-Bird.

Learn of Fabius Bile’s Cloned Primarchs and other Dark Experiments



~ Reflect long on the abyssal fall of such a man, and steel yourself against such a fate.

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