Regency of Deneb
The collapse of the empire wasn't based on the incoherence of the emperor, nor the gall of Dulinor, nor even the insanity of Lucan. It was the fact that no sane voice cried out with the voice of universal reason.
Everyone simply accepted that the emperor WAS the empire, and they had to simply accept that fact. When Dulinor and Lucan, both of whom had a legitimate claim to the throne, started to act like churlish children, it set a bad example for everyone. Nobles like Brzk and Craig and Margaret and many others would reach a point where they could no longer bear the spectacle and each would make their own beeline for the fire exits. And as the bigger levels of government collapsed, the supporting substrata at the subsector and planetary level would eventually make the same decision of progressive abandonment, as these successor nobles burned themselves out.
The only region that did not accept this progression was the Domain of Deneb. But that was almost as much by accident as design. Deneb was very different than the rest of the Imperium largely because of its isolation and distance from Capitol. Its settlement was the Imperium in a microcosm, and it had an informal tradition of self-rule that had been first set down during the Civil War. When Lucan withdrew the Corridor Sector Fleet, the Domain was cut off from the rest of the Imperium by subsequent Vargr invasions of Corridor. Thereafter its unity was severely tested by invasions from several quarters, and a growing sense of helplessness as the Final War escalated to the level of genocide and ecocide. The linchpin of unity during those dark years was the "Archduke" of Deneb, Norris Aledon, who refused to abandon the empire for many reasons. Norris was able to rally the Domain to its ramparts, and managed to defeat or stem the tide of Aslan and Vargr invasions.
After sending an force recon mission to Usdiki to meet with the "Real" Strephon, the Archduke received official recognition in more ways than one. The emperor not only confirmed his appointment, but sent along his only son, Avery, as a means of demonstrating that the Domain was the true inheritor of the Imperium and its principles.
Three years later Dulinor released the AI Virus during his bungled final attack upon Capitol, and what remained of interstellar society in the core of the Imperium quickly succumbed to the contagion's assault on war ravaged data networks. As the virus consumed these sectors, emergency notification was sent to Deneb from Usdiki, and the Domain Navy and Scout Service quickly mobilized to seal off the Domain's borders from infection. With the Imperium now all but dead but in name, Norris had to act quickly to establish a new government. After securing the cooperation of the Zhodani Consulate and other Spinward states behind the Great Rift against the spread of Virus, the Archduke established himself as the Regent of the Regency of Deneb in IY 1132.
By taking such decisive action, Norris established in fact what Strephon had hinted at: the new state was the legal heir to the Imperium. In spite of the darkness of war, the people had stayed steadfast to the principles of the Imperium. Norris himself took these alleged principles and the bravery and example of his people to wend together the icon of the "Flame". According to him, the Flame was the beacon of timeless and transcendental values that would guide them through the night of Virus and back into the light of the promised land of a new Imperium.
Source:Peter Gray