I won't dwell too much on the Necrons' origin however if you are curious about them, you can read this Aux chapter.
====================
Long ago, in the vast universe of Warhammer, the Necrons did not yet exist. Their ancestors, the Necrontyr, were a frail and cursed species born under the blinding, radioactive gaze of a cruel star. Their homeworld was harsh, battered by radiation that ravaged their bodies. Cancer and sickness spread like wildfire, and the Necrontyr lived short, agonizing lives, knowing nothing but suffering.
Despite the odds, the Necrontyr were resilient. Against all reason, they reached the stars, becoming a space-faring race. But their triumph was short-lived. Even as they colonized new worlds, escaping the surface of their dying planet, the curse followed. Their children, born light-years from the homeworld, still bore the same radiation scars. The life expectancy never improved. They could leave their planet, but they couldn't escape its shadow.
As they spread across the galaxy, new dynasties rose. Eventually, they encountered the Old Ones, an immortal race of unfathomable intelligence. The Old Ones were architects of life, seeding planets with their knowledge and guiding evolution. To the Necrontyr, they were gods. In their desperation, the Necrontyr pleaded with the Old Ones, begging for the secret to immortality that could save their dying species.
But the Old Ones refused. Bound by their own code, they chose not to intervene. The Necrontyr's fate was their own. This rejection shattered the Necrontyr's spirit. Rage and hatred festered, and, despite the hopelessness of such an endeavor, they declared war on the Old Ones. The Necrontyr's anger, however, could not match the Old Ones' superior technology and power. Defeat followed defeat, and the Necrontyr's dream of vengeance seemed destined to die.
But fate took a dark turn. In their search for power, the Necrontyr encountered the C'tan, star gods of immense power—beings who fed not on life, but on the energy of stars. These ancient creatures, once formless and bound to the cosmos, promised the Necrontyr the strength they craved and the immortality they desired. They spun a tale of hatred for the Old Ones, seducing the Necrontyr with promises of revenge.
Blinded by their desperation, the Necrontyr struck a deal with the C'tan. They crafted bodies of living metal for these beings, allowing the star gods to take physical form. In return, the C'tan gifted them weapons and machines of incredible power. The Necrontyr worshipped the C'tan as saviors, believing that through them, they would finally bring ruin to the Old Ones.
But the C'tan's most seductive promise was yet to come: immortality. To escape their frail, cursed bodies, the Necrontyr agreed to undergo a process called biotransference. Vast furnaces were built, designed to burn away their weak flesh and replace it with living metal. The first to enter the furnace was the Silent King, their ruler. As his body was transformed, he felt immense power—but something was wrong. He felt hollow, empty. His soul was gone.
One by one, the Necrontyr underwent biotransference. Some went willingly, others were forced. Their bodies were disintegrated, their souls consumed by the C'tan. When the process was complete, the Necrontyr were no more. In their place stood the Necrons—immortal, soulless machines. The C'tan had feasted on their very essence, leaving only hollow shells.
The Silent King, now bound to his soulless form, realized too late the horror of what he had done. His people, once united in their quest for survival, had become slaves to the C'tan. Though the Necrons were now unstoppable, their eternal lives came at the cost of their very souls.
With their new power, the Necrons and the C'tan waged war on the Old Ones, burning entire worlds, extinguishing countless species created by their enemies. The galaxy trembled as the Necrons marched forward, and the C'tan feasted on the souls of the living. The ancient empire of the Old Ones was torn apart, and their legacy was erased from history.
The Necrontyr were no more. In their place stood the Necrons, eternal and hollow, bound to a fate far worse than the one they had tried to escape.