The Serpent's Whisper
The Laeran blade was no mere weapon — it was a vessel containing a powerful daemon of Slaanesh. From the moment Fulgrim claimed it, the daemon began its work, praising his every achievement while stoking his deepest insecurities. Fulgrim, already obsessed with perfection, was uniquely vulnerable to such manipulation.
The blade convinced Fulgrim that the Emperor was holding him back, that his true potential could only be realized by casting off all restraint. It whispered that perfection required freedom from morality, from duty, from loyalty itself. Slowly, inexorably, the Primarch was turned.
Istvaan III — The Betrayal Begins
When Horus rebelled, Fulgrim was among the first to pledge allegiance to the Warmaster. The Emperor's Children were tasked with purging their own Legion of loyalists on Istvaan III. Those Marines who remained loyal to the Emperor were condemned to die alongside the loyalists of other Legions.
The bombardment of Istvaan III was a massacre. Thousands of loyal Space Marines were killed from orbit, their bodies burned to ash before they could even fight. Among the dead were some of the noblest warriors of the IIIrd, including Captain Saul Tarvitz, who had tried to warn the Imperium of the coming betrayal.
Istvaan V — The Dropsite Massacre
The betrayal at Istvaan V was even more devastating. The Emperor's Children, alongside the other traitor Legions, lured the loyalist Legions into a trap. As the Iron Hands, Raven Guard, and Salamanders deployed to the surface, they were surrounded and annihilated.
The Emperor's Children fought with a savage joy that horrified even their allies. They had abandoned all pretense of discipline, embracing the chaos of slaughter. Fulgrim himself slew Ferrus Manus, Primarch of the Iron Hands, in single combat — though the victory was tainted by the daemon's influence, and Fulgrim wept even as he struck the killing blow.
The Path to Damnation
After Istvaan, the Emperor's Children descended further into depravity. They pursued sensation without limit — the thrill of battle, the ecstasy of violence, the pleasure of excess. Their armor, once gleaming purple and gold, was defaced with chaotic markings and the symbols of Slaanesh.
The Legion fractured into warbands, each pursuing its own dark desires. Some became obsessed with collecting the skulls of their enemies, others with the perfect symphony of screams, still others with the art of pain. The unity and discipline that had once defined the IIIrd was gone, replaced by a cacophony of individual obsessions.
The Final Transformation
Fulgrim ultimately succumbed completely to the daemon within the Laeran blade. In a moment of ultimate horror, the daemon claimed his body entirely, transforming the proud Primarch into a writhing, serpentine daemon prince of Slaanesh. What remained of Fulgrim's soul was cast into the depths of the Warp, and the Emperor's Children — now little more than a legion of debased hedonists — followed their daemon Primarch into the Eye of Terror.