Not much is known of her early life, Anzat Living for a very long time, possibly millenia as long as they feed on other sentient beings. Besides most records of her birth, which include her parents names, location and any other details on who she really is would have been either lost, or destroyed by her, as anything exposing her as being an Anzat would most likely make her life much, much harder.
What is known is that by human standards, she has already outlived at least a few generations. Anzat don't reach puberty untill they are around 100 human years old and its pretty clear that she is long passed that, she is obviously a highly trained and effective assassin, she has more than likely hunted and fed on jedi well before she is even was a sith as Anzat learn very quickly that force sensitives can enhance her connection to the force and by connection, her powers if they are fed on, Anzat who generally feed Jedi or other force sensitives are said to be both rare and terrible creatures.
Darth Keres was raised as sith and thought for a long time to be some experiment on Korriban possibly crossbreeding or genetic engineering of both Anzat and non humanoid species, the idea of which was to enhance the predatory instincts of the Anzat and couple them with other possible combinations in the hope to make even more efficient, long lived, brutal killers and to use others at weapons of terror to unleash on colonies and purge them of life.
While some of these experiment were sucesses... Some becoming near immortal killers with a taste for human flesh, brutal creatures living only to kill, however, recent accounts and records show she we present long before these creatures started appearing around the galaxy, and there is evidence that she might have been the source of the Anzat DNA needed for these abominations, Kres was already well versed in sith alchemy according to some, others have her as the head of these experiments spawned from her own blood, essentially making Keres their mother.
Keres is an efficient assassin. She had developed an extreme taste for human pain and blood at a young age. Finding out what she what she was has allowed her to distance herself from her prey. She is not human and she knows it, making her a danger to all sentient beings.
~PRIORITY TERMINATION REQUIRED~
Darth Keres made her way to Rakata for answers but ended up taking training by the Sith Ancients under Darth Mephistus with her sister Darth Chaos. Chaos attained the rank of Darth soon enough, but Keres wanted to learn as much as she could. She stayed quiet but grabbed every bit of training and knowledge she could. She kept on training under Mephistus and became second in command of Darth Reverance's Sith strike team. However, soon after Adazca's fall she quit the Sith Ancients along with Chaos, Reverance, and many others. They had become a shadow of themselves, her master had gone and it left Keres' with only her sister, Chaos.
Assassin For Hire
Keres and Chaos quit the Sith but they could not control the darkness inside them enough to let it die and they loved it enough to keep feeding it. With a band of other disgruntled sith they formed a group of well trained killers. It went quite well for awhile but unfortunately the bigger fishes would have none of that. More powerful crime syndicates saw fit to either destroy the assassins or buy them out. Finding the first too complicated they opted for the second choice and bought them out. Chaos and Keres switched clans yet again and now worked for the Mandroxian Syndicate, the largest crime syndicate in the galaxy at the time.
The largest criminal organization at the time, the Mandroxian Syndicate, had a powerful artifact in their possession that made them the group most in demand. Getting allied with the Dark Ancients (Formerly Sith Ancients) proved to be the Syndicate's downfall however, as certain Mandalorian Groups and Sith wanted the artifact. The Syndicate's enemies staged attacks and the Mandroxians were forced to form alliances with the Jedi and the Dark Jedi. The Jedi and Dark Jedi both turned on the Mandroxians after they all failed to agree on the use of the artifact. The Jedi wanted it destroyed and the Syndicate wanted it sold to the highest bidder. The Syndicate ended up being destroyed and soon after most of its members were arrested by the Fel Empire established on Bastion when a contract went sour.
Imperial Empire Fel
Keres and Chaos had been brainwashed in forgetting their Dark Past, the Syndicate members were given three choices: Jail, death or military service. They both chose the latter with Keres being assigned to the 101st Dark S.P.E.A.R. SpecOps. She was trained in their facilities at Bastion and then she was assigned to be the team's shock trooper. Keres was trained to operate missile launchers, anti-armor weapons and heavy machine guns and other heavy artillery as well as to pilot fighters and transport ships. She was a skilled pilot capable of delivering the final blow to an attack...
After a failed mission the team's captain, Indur Rakosi, stepped down, feeling unable to control his unit. Keres had shown herself in her manipulative and deceptive actions to have Rakosi leave command to her to lead the S.P.E.A.R.
An alliance with the Dark Jedi would prove to be their own downfall again. The memories of their last alliance with the Dark Ancients, still fresh in her skull, left her and Chaos wanting them dead. The Dark Ancients ambitions included taking over Byss and destroying or kicking the Sith out completely.
It was during that time that Keres' former Master, Darth Mephistus, showed himself again. Mephistus had been forced into hiding for being loyal to his own master, Darth Adazca. Adazca was all but killed by the Dark Lady Raven just before she turned the Sith Ancients into the Dark Ancients, the Dark Jedi. Mephistus now called for Chaos and Keres.
New Sith Ancients
Keres willingly gave into the Dark Side yet again, embracing it and once again enjoyed the power it gave her over life and death. She fell so deep to the Dark Side that still in command of the S.P.E.A.R., she ordered innocents murdered on her last mission with the unit before she left and rejoined the sith. Unknown to the others in the squad it was already too late and that she was plotting their demise and Chaos' return to the Dark Side.
Darth Keres tempted her sister, Darth Chaos, to join her and it forced the two sisters to fight each other on Naboo. Forced to strike down Keres, Chaos reawakened. Chaos did not kill Keres however, and she was only knocked unconscious which was Keres's plan all along knowing her sister couldn't kill her but striking her down was enough to crush her sisters will to stay behind.
Darth Chaos returned to the Imperials that were aboard their ship and in a surreal state dropped Keres nearby to the ship. Chaos then attacked the Imperal forces on her own, killing most. She then called for Keres to assist her.
Keres boarded the ship undetected and cloaked by the force. She reappeared behind the Grand Admiral who was too busy with Chaos to even notice her. With a dark grin on her face and an evil growl, Keres placed her cold and bloody hand on his chin. Keres pulled his head back and sliced his throat with a short lightsaber. They had betrayed the Imperials, killed most and vowed to destroy those who had escaped and all who aided them. In a last act of violence, Keres and Chaos destroyed all life on Bastion and left the planet unscarred but all life on it violently ripped out.
The Sith Ancients II
Keres and Chaos had returned to the newly reformed Sith Ancients with blood on their hands and death on their minds. What happened on Bastion had only left Keres lusting for more. She had returned to the Sith colder, deadlier, and more sadistic. Any good left in her had died at this point. She did not wish for power as much as she wanted to see everyone and everything dead or suffering at her feet. Constant attacks by the remaining Imperial forces and their allies left her tired but still lusting for revenge.
She gave in to her lust for death and suffering. Keres experimented with the darkest possible forces she could. Praising misery, grief and suffering as her weapons of choice, she often using live subjects to torture. She found new ways to mangle their flesh and minds fiercely loyal to the ancients, but most of all to her sisters she fought all those who wished to stop them.
Keres took an apprentice and she brutalized her to no end, going as far as shoving her head in the Byss lava to disfigure her. The apprentice eventually failed her and Keres knocked her out, near killing her. She tied her to a table and inflicted on the apprentice the worse tortures possible. She was kept alive for days and days. In a dark sick and twisted ritual Keres drank the girl's blood and made herself a sith mask with the apprentice's skull she had slowly cut off while the girl was alive. The Keres' Mask was inbued with Alchemy and the Dark Side. It can make people, even other sith feel either intense fear or very ill.
The Imperials were then gone and the Dark Ancients were left reeling. After the fall of Byss, the Sith Ancients relocated to Ziost and despite the Sith order's drive to destroy the Light, it fell apart. Darth Keres was left alone with her sister, Chaos. Surya was dead and Darth Andraste had taken her place. Mephistus and Adazca yet again exiled themselves. The rest fell and most of the sith turned on each other or quit leaving the Sith Ancients in ruins.
Keres then either went into hiding with Chaos or assumed another identity. Reports are that she might have disguised herself as a bounty hunter. Darth Keres still killed in cold blood and made sure to cover her tracks, ensuring she could not be traced but this is only speculation.
Still the call of the Dark Side was too strong and Keres reappeared some time later, her plans clear as day now. Destroy the weakness that has been allowed to prosper in the Galaxy. The False Sith. The Jedi. The Mandalorians. The Imperials. They had to be destroyed and Darth Keres began quest to eliminate the scum in the galaxy.
The Assembly of Darkness
Chaos and Keres stumbled onto Vjun sometime after, and were taken in by Lord Kestrel and the Assembly of Darkness, they felt Vjun was the best place for them to carry out their plans to kill the Light and lead the Dark Side to control of the Galaxy.
Darth Keres was one of the Sith Masters on Vjun in the Assembly of Darkness and sat on the Sith Legends Council as the Minister Of Order on Ziost. Also she was a Darth in her sister Darth Nemu's Sith order on Manaan.
Keres' main goal has not changed. Total destruction in the worse possible way of the Light and any of its allies. However Darth Keres' even darker side has recently been showing up more and more recently. She might be willingly letting herself be consumed completely by the Dark Side. Maybe it is what she had been made for, letting it raise to the surface.
She sees most other living things as prey, showing no compassion at all while slaughtering them. Worse yet, Keres has developed an even finer taste for grief. Often letting one person live in order to kill all those it loves. Keres forces people to do as she wishes or be forced to watch those they loved to be slowly tortured.
Also now Darth Keres has developed means of mental torture rarely seen. Wiping even strong Jedi's minds and blocking any memories of their past with images of death and torture. Keres makes it physically painful and eventually deadly for them to even attempt remembering those blocked memories.