In the aftermath of the first skirmish with the Eternal Fleet in 3636 BBY, two prominent figures of the ongoing Galactic War—Darth Marr and the Outlander—were taken prisoner and brought before Emperor Valkorion of the Eternal Empire of Zakuul. Darth Marr instantly recognized Valkorion as the new face of Sith Emperor Vitiate, who had abandoned his Sith Empire and even destroyed all life on the Imperial world of Ziost. Valkorion stated that there were no limits to his power and offered Darth Marr to kneel to before him, and when the Sith Lord angrily refused and attacked Valkorion's Knights of Zakuul instead, killed the leader of the Dark Council with a single Force blast. Valkorion then made the same offer to the one remaining Outlander, but Prince Arcann, the spiteful son of Valkorion, took advantage of this moment to attack his father, resulting in the death of his physical body. Having already endured deaths of multiple host bodies over centuries, Vitiate's spirit attached itself to the Outlander, whom Arcann ordered to be frozen in carbonite intending to trap his father forever, alone and forgotten. Arcann then immediately seized the Eternal Throne and proclaimed himself the new Eternal Emperor, blaming his father's assassination on the Outlander regardless of their involvement and beginning a conquest against the Core Worlds for what he claimed was an act of unprovoked aggression.
In addition to being the Emperor of the reconstituted Sith Empire for over thirteen centuries, Vitiate had also created a secret Eternal Empire in the Wild Space, ruling from the Eternal Throne on Zakuul as Immortal Emperor Valkorion. Following the rejuvenation of his spirit during the Battle of Yavin 4 and the subsequent Devastation of Ziost, Vitite had completely abandoned the Sith Empire and focused all of his attention on Zakuul. Valkorion's biological sons Arcann and Thexan had recently come of age and performed a series of brutal raids on several galactic worlds, during which Arcann lost his left arm and received significant facial scarring, requiring extensive cybernetics.
Arcann's first attempt to strike at his father.
When his sons returned with trophies from defeated enemies, Valkorion turned away from them, and angered at his father's indifference, Arcann attacked him. Thexan intervened, and in a brief exchange of blows that followed Arcann inadvertently struck his brother down. Not long afterwards, a joint Imperial-Republic task force approached Zakuul's territory for the first time, and Valkorion send the Eternal Fleet in response. In the resulting battle, the invading ships have been completely destroyed, while Arcann recovered two survivors, Dark Council leader Darth Marr and the Outlander of great importance to the ongoing Galactic War. The prisoners were brought to Arcann's Eternal Flagship, which departed with them back to Zakuul.
Valkorion and Arcann receive their prisoners.
Shackled and disarmed, Darth Marr and the other Outlander were brought by Prince Arcann directly to the Eternal Throne room. Darth Marr immediately identified the Immortal Emperor as just another host body of Sith Emperor Vitiate, though the Outlander still remained incredulous that he could build a whole other Empire in total secret. Neither acknowledging nor dismissing their claims, Valkorion bluntly stated that the fate of galactic Core Worlds and people on them did not concern him and offered Darth Marr the chance to kneel before him, removing his shackles with the Force. However, Marr was enraged by silence and indifference of the former Emperor who abandoned the Sith Empire and refused to kneel before him ever again. He Force-pulled a lightsaber pike from one of the Knights of Zakuul that guarded the Throne room and proceeded to attack them, killing at least two.
Darth Marr defies his former Emperor.
Valkorion then killed the Sith Lord with a powerful blast of concentrated lighting, at which point his daughter and High Justice Vaylin ordered all Knights and Scions of Zakuul to clear the room. Arcann and Valkorion were left alone with the Outlander, whom the Immortal Emperor once again asked to kneel, offering to share his power with them in return. At this point Arcann, who continued to despise his father for ignoring his ambition, seized the moment and used Valkorion's preoccupation with the Outlander to once again attempt to strike him down. In the resulting chaos, Valkorion's physical body received a mortal wound, while Vitiate's spirit refused to surrender to mortality and entered the Outlander's body in search of a new host. The resulting release of energy knocked the Outlander unconscious and Arcann used it to blame Valkorion's assassination on them. However, he sensed that his father's spirit was still present inside a new host body and ordered the Outlander to be immediately frozen in carbonite.
Arcann became the new Eternal Emperor after his father's death.
His father no longer in his way, Arcann immediately assumed his Eternal Throne and proclaimed himself the new Eternal Emperor. He claimed that the Outlander had assassinated Valkorion for seeking to destroy Zakuul society and promised revenge on the Core Worlds, launching a full-scale Eternal Empire conquest in retaliation. Within a year, the might of the Eternal Fleet and the strength of the Knights of Zakuul overpowered the Galactic Republic and the Sith Empire, forcing both to sign peace treaties and pay heavy tribute to Zakuul. Arcann believed that he had condemned his father to a fate worse than death, trapped inside a body that he could neither leave nor use to escape. Indeed, Valkorion was tied to the Outlander, but his new host had shown an unexpected resistance and retained control of their mind and body, forcing Valkorion to use deception and attempt to gain their trust instead. Valkroion showed the Outlander visions during their shared carbonite imprisonment and also used the Force to save them from death by carbonite poisoning caused by imperfect carbon-freezing process. His Empire left undefended, Darth Marr also refused to perish and persisted as a Force ghost, able to manifest himself on different worlds in the galaxy unlike most Sith spirits, who usually remained bounds to their tombs or artifacts.
Whether by the player or by his son, Valkorion is caught by surprise and killed.
During Knights of the Fallen Empire Chapter I: The Hunt player can either accept or reject Valkorion's offer of power, neither of which is a Light or Dark side choice. If the player accepts, Valkorion begins to empower them with his essence, only for Arcann to do what the player could not and stab his father in the back. If the player rejects the offer, Valkorion orders Arcann to kill them, only for Arcann to cut the player's restraints and throw them their weapon, so that they could attack the Emperor together. Arcann will attempt to land a blow on Valkorion, who will easily block his son's direct attacks, only for the player to seize the opportunity and stab/shoot him in the back instead. In any case, Valkorion's spirit attaches himself to the player, who is publicly blamed by Arcann for the murder, and the overall events play the same, although the choice will still be referenced by Valkorion in dialogue several times during the subsequent events.