- "The dark forces that assail Humanity will never cease their attack, and so neither shall I. The Traitors, the Heretics, the aliens – they began this fight, but we shall be the ones to finish it. The Emperor expects no less. Our enemies wield terror and cruelty as their weapons, thinking they can cow us into submission. I wield a crushing gauntlet and a damned enormous laser as mine, and I shall never submit. Were I a betting man, my lord, I know where I'd put my coin."
- —Sir Hekhtur the Chainbreaker, to Governor Doslyn before the Battle of Narsul Sound
Canis Rex is a unique Knight Preceptor piloted by Sir Hekthur Cerberan, a Freeblade known as "the Chainbreaker," who was once a scion of House Cerberan, which ruled the Knight World of Randoryn Alpha. After his homeworld and house fell to conquest by the Heretic Astartes of the Iron Warriors Traitor Legion, Cerberan prayed to the Emperor for a miracle while the Chaos Space Marines tortured him.
His prayers were answered when his Knight Preceptor's Machine Spirit activated his war machine on its own and aided him in his escape. Now Cerberan and Canis Rex travel the galaxy, seeking to free all those in the Imperium who have been oppressed by Chaos and more mundane tyrants alike.
- "There are none so detestable in all the length and breadth of the Imperium as those who make slaves of its loyal servants. Honest toil in the Emperor's name is one thing, for through industrious labour and needful hardship does a man ready his soul to receive the Emperor's grace. But when the alien or the Heretic places the yoke of slavery upon the necks of honest Imperial citizens, and turns their good works to foul ends, that is a sin of unforgivable magnitude. There is only one punishment fitting for such abominable tyrants...Death"
- —Sir Hekhtur the Chainbreaker
When the Iron Warriors attacked the Knight World of Randoryn Alpha, the Knights of the ruling House Cerberan marched out in force to deny them. The campaign was gruelling and merciless, the tides of battle flowing back and forth across the planet's rugged equatorial landmass. The Knights broke the Heretic Astartes lines time and again, their magnificent charges shattering the Iron Warriors' strength and destroying their armoured siege trains. Yet one by one, the Knight suits fell or were crippled; one by one the strongholds of House Cerberan were besieged and laid low, and their serf chattel enslaved by the millions.
After a final, courageous stand before the gates of the Stygian Keep, House Cerberan was defeated. The last of its Knight suits were disabled by invasive electrogheists, their pilots hauled out for torturous reconditioning.
Sir Hekhtur Cerberan was amongst those taken captive. The house's only surviving precept, the gruff old Noble did his best to inspire and bolster his comrades. Yet the horrors that the Iron Warriors inflicted were beyond imagining, and gradually they wore down the surviving Knights. As each warrior's spirit broke, so their Knight suits too were corrupted and transformed into heretical engines of destruction. Yet still Sir Hekhtur held out, chained within a dark oubliette, praying to the Emperor for deliverance.
Some say the Master of Mankind heard Hekhtur's prayers and sent him a miracle to reward his honour and faith. Others claim that Hekhtur's unusually strong bond with his Knight, Canis Rex, was the cause of the strange events that followed. Whatever the reason, all agree that Hekhtur was rescued from captivity by his Knight suit. Unpiloted, acting purely under the direction of its ferocious Machine Spirit (artificial intelligence), Canis Rex tore free of the Iron Warriors' remaking engines and blasted a path to its pilot with its Las-Impulsor. Freed from his chains, and with his captors in disarray, Sir Hekhtur was able to mount his Throne Mechanicum and -- reunited with Canis Rex at last -- make good his escape.
After taking the Freeblade oath as the last loyal Noble of his house, Sir Hekhtur led the Randorynian resistance, fighting back against the Heretics wherever he could. He freed many enslaved serfs and managed to ferry them off-world to safety, earning his Freeblade epithet, "Chainbreaker." Yet eventually even the grimly determined Hekhtur was forced to accept that his world was lost to the servants of Chaos.
Rather than throw his life away, Hekhtur took Canis Rex and the small complement of loyal Sacristans he had managed to save, stole an Imperial frigate, and set off to find a war that he could win for the Imperium. He and Canis Rex have voyaged the stars ever since, freeing Imperial citizens enslaved by foul oppressors and punishing the scions of Chaos with vehemence and fury.
- Archeotech Laspistol (Sir Hekhtur's sidearm)
- Freedom's Hand (relic Thunderstrike Gauntlet)
- Ion Shield
- Titanic Feet
- Codex: Imperial Knights (8th Edition), pp. 54, 67, 98