Come and find out how this Knight House turned its back on the Emporer and quickly realized that that was a mistake.
House Vyridion was a one noble Knight House but during the Heresy, they chose the wrong side and came to realize the mistake that they had made Let’s see what price they had to pay for their treachery.
Via: Lexicanum
House Vyridion established itself on the world of Highrock and was discovered by the Primarch Fulgrim during the Great Crusade. After hearing of the Emperor and his vision for Mankind, House Vyridion joined the Imperium and swore an oath of loyalty to Fulgrim; their Knights then went on to fight beside the Emperor’s Children Legion for three generations during the Crusade.
Because of this when the Horus Heresy began, they were unaware of Fulgrim’s fall to Chaos and under the leadership of Baroness Jaya D’Arcus they readily answered his call to war against those he claimed had betrayed the Imperium. Under Fulgrim’s command they joined the Emperor’s Children in conquering two of the Imperium’s worlds; though they began hearing rumors that Fulgrim and his Legion had turned upon the Emperor.
The Household had no way to verify these rumours though, so they continued to fight under Fulgrim and repeatedly came to his defense when his forces were attacked by the Imperium’s forces. They would be responsible for the deaths of hundreds of Iron Hands and thousands of their Imperial Army allies and later aided the Emperor’s Children in fighting the Knights of House Riathan at the Battle of Mount Galheim.
However, it was this battle that caused their loyalty to Fulgrim to begin to fray, when the Knights of Riathan implored House Vyridion to see reason and began transmitting the wider war details of the Horus Heresy to them.
After seeing this eye opening information, House Vyridion was left unable to determine whose side in the Battle of Mount Galheim truly fought for the Imperium and refused Fulgrim’s next orders to attack the Knights of House Riathan. Instead they immediately retreated to their ship and returned to their Homeworld Highrock and where they left their Knight suits within their fortress, the Great Vault.
Two Thirds of the Knights and a few of their Sacristans, then traveled to Terra in order to finally learn the truth of what had happened during the Horus Heresy. Once there however, the Knights and Sacristans were immediately imprisoned within the Seberekan Isolation Compound and were faced with being executed for their actions while they fought under Fulgrim’s command. They remained imprisoned for sometime, until the Adeptus Custode Diocletian Coros told them they would be pardoned for their crimes, and given a chance to regain their honour, if they aided the Imperium’s forces fighting in the War Within the Webway.
The Knights immediately agreed and asked Coros to return their Knight suits to them, but the Adeptus Custode told them that it was no longer possible to do so. He explained that weeks after the Knights had left Highrock for Terra, the enraged Emperor’s Children had invaded their Homeworld and turned it into a lifeless wasteland; because the Knights had defied Fulgrim’s orders.
Though they were left devastated by the news of Highrock’s destruction, the few Knights and Sacristans that remained of House Vyridion readily agreed to aid the Emperor and were supplied with cast off Knight suits from loyal Knight Houses as well suits captured from traitor Knight Houses.
They would then go through the Webway Portal located in the Imperial Palace and reached the Imperium’s last stronghold in the Webway, the Eldar city named Calastar, just as the hordes of Chaos began overrun it. House Vyridion would fight to save Calastar, before the order to retreat back to the Webway Portal was given, and they then aided in defending the retreating Imperium forces reach the Imperial Palace; where the Emperor then sealed the Gate and ended the War Within the Webway.
What became of House Vyridion afterwards is unknown, but the Emperor had a standing order that anyone who entered the Webway, other than the Adeptus Custodes, Sisters of Silence and the Mechanicum, was to be put to death.
