Here is my little SW:TOR AU that happens during all the storyline, a storyline outside the canonical storyline, if you will. Enjoy. And all but my ideas in this fanfiction belong to Bioware and EA.
3,659 BBY; Underground Ritual Chambers, Imperial Citadel, Kaas City, Dromund Kaas
Darth Marr was unsure of what to make of the twisting Labyrinth that was located beneath the Imperial Citadel on the Capital world of Dromund Kaas and knew from historical records that Darth Nostrem had reconstructed the Citadel from the Emperor's original design and then the Emperor had cast Lord Nostrem – the only person other than the Emperor and his Hand to have knowledge of its underground pathways – into the Labyrinth to test its defenses, and then the Dark Lord had not been heard of since… but remembered as another Sith who was one of the greatest architects of the Empire with his masterpiece being seen from anywhere in Kaas City.
And now Darth Marr found himself walking these hallowed halls with only a member of the Emperor's Hand as a guide and couldn't help but fear, not just for his own life but the life of the sleeping two year old in his arms that his Mandalorian Wife had died to bring into the world, the Emperor had been insistent that Marr was to bring his toddler son and how was a Dark Lord of the Sith to deny a Sith god of his wishes and desires? So he was here now, with his son as he had been commanded, walking possibly into the hands of a deity-level Sith.
"Welcome, Lord Marr," announced a voice, and that was what Darth Marr literally saw, the Voice of the Emperor stood as in the human form he was back when he had led Darth Thanaton – the then Teneb Kel – to him nineteen year prior.
The Emperor stood just within the Chamber that stood at the end of this corridor and the room that the Emperor had apparently called him to, the Voice backed up into the room and motioned elegantly with a free hand for Marr to move deeper into the Room and soon the member of the Dark Council knelled down before a dais, within the dais was a deep spherical trench which Marr would recognize as a massive black marble bowl that seemed to be filled to waist height with a muddy blood color liquid. And Marr suddenly felt fear again, was this some sort of pool for rituals that included human sacrifices? Was his life forfeited or his son's?
"You need not fear Lord Marr, a bountiful boon awaits not a graveyard of despair," spoke a member of the Hand.
"What Servant Two clearly means, is that you worry for nothing when all the Empire wishes to do is reward you through your son while you bare witness," stated Marr's escort, evidently the 'leader' of the Emperor's Hand.
What Darth Marr noticed about the Emperor's Hand was that each of their number were Sith Purebloods and that could attest to their loyalty to the Emperor, he was Emperor of the Sith Empire and every Sith – Pureblood and not – within it, the hand were effortlessly loyal to their Emperor and so long as Darth Marr would be allowed to strengthen and forge the Empire through conflict, then so would Marr too be absolutely loyal to the deity of Chaos and Darkness before him.
"Indeed," stated the Voice, calmly "Exal Kressh too misunderstood what I intended to do to her, she thought I wanted to hollow her out to make her become a mindless drone, when all I seek is an Avatar to represent my will on this mortal plane for my ascension to Divinity or at worse… a successor to inherit my essence and to continue my legacy."
"The merciful and bountiful Emperor wishes to reward you for your years of service in leading and defending his glorious Empire, by choosing your son to be his Avatar and to one day lead the Empire to greatness!" announced Servant One, speaking for his Emperor.
"As he saw, through the visioning eyes of Twilight trapped in a Maelstrom," stated Servant Two, a pleased smile on his tentacle face.
The Voice motioned and Darth Marr answered as he grudgingly stood to his feet to hand his son over to the Sith Emperor who smiled blankly at his servant, the Emperor turned while hushing the murmuring child and then frowned when he noticed something on the child's face, already down two steps and already foot deep into the blood red liquid of the bowl which he took a moment to skim the face of the child that would in fact be his face one day and represent the Sith god to the Emperor's people.
"What is this… disfigurement, this… tattoo over his left eye?" questioned the Voice, a glare sent in Darth Marr's direction.
"A sign of Mandalorian respect, my Emperor," explained Darth Marr, cautious with his words "the Mandalorians tattoo themselves often, my Wife was Mandalorian and the last request she made was to tattoo him over the left eye, with the ancient symbol of their Destroyer God: Kad Ha'rangir."
The Voice of Chaos and Darkness chuckled to himself, "The God of Conflict and Destruction, personifying change and growth through the former mentioned traits, how fitting."
The Emperor said no more however as the Voice continued his descent into the blood red pool until he stood at its center and was waist deep, the twelve members of the Emperor's Hand stepped to the edge of the pool and began to chant the lines of the Ritual that there Emperor had long since prepared for them, soon the Emperor's Voice also joined the chant as a Force Storm wracked lightning about the room and the stone braziers suddenly had their flames turn a blue color.
All became silent and dark however, as the Voice reached the ending of his spell and dunked the toddler in a primitive form of baptizing as the flames quieted, drawing the room into a quiet and eerie, near darkness.
3,648 BBY; Training arena, Darth Marr's Estate, Kaas City outskirts, Dromund Kaas
Ever since that day, Darth Marr had taught his son discreetly in the ways of the Dark side of the Force and had called him by the name that the Sith Emperor had baptized him with: Callidus, an ancient Rakata-Sith languages translation that was familiar with many species, it was a primal word but its meaning was obvious – cunning, the Emperor had charged Marr with making his son a member of the Dark Council so that he would be in a position of power to cunningly manoeuvre the Empire into a suitable position against the Emperor's enemies and have experience to take the Immortal throne the Emperor would leave behind after his ascension – to become the immortal personification of the Emperor's will in the mortal world.
Callidus had a prodigious learning streak and rapidly took in knowledge that was far beyond even someone twice his age, he seemed to have photographic memory and high speed adaption allowing him to learn that which had taken Darth Marr years as an Acolyte to learn himself, like his older sister Callidus had been experimented upon while in the womb and therefore he had been specifically 'designed' to be stronger and smarter than a naturally born child.
Darth Marr had been sure that his son had been 'enhanced' by a private biologist rather than someone from the Sphere of Biotic Science, as a Sith Lord he had to worry about rivalries among his fellow Dark Councillors and their own attempts to gain further power, Darth Marr had been told that his son would not be born Force sensitive and therefore when he was born extremely powerful in the Force coupled with the genetic modifications made to him in the womb became too much for Darth Marr's loving wife who had expired not too long after giving birth.
"He is impressive," commented Darth Decimus, from where he stood nearby.
Indeed Marr could only watch as Callidus danced between two of Darth Marr's apprentices, with one being Darth Lachris, bolts of Force lightning arched from Lachris's free hand but Callidus merely performed the feat of lifting metal floor plating into the lightning's path. Callidus simply used the distraction to Force leap over the piece of metal as the lightning projected it past where Callidus had been standing, before swinging his training sabre at her left side which she almost failed to catch on her own training sabre, Marr's second apprentice approached from Callidus's rear but Callidus managed to roll out of the way and catch the surprised apprentice with a powerful Force push.
While he was distracted however he was set upon by Darth Lachris, who bombarded him with Force lightning in the back but Callidus refused to go down, standing as stiff as a statue and using the immense agony of the lightning to strengthen his connection to the Dark side of the Force. Darth Marr decided to intervene however when Callidus channeled his power in the Dark side to generate blasts of Sith magic, abilities that he was sure that he had not taught his son to use, and Marr once again considered the possibility of the Emperor's interference in his son's teachings.
"I am going to have you put into a sink or swim situation, you will be subordinate to Darth Decimus and given the rank of Sith Lord," announced Darth Marr, as he looked down at his kneeling apprentice son "you will be known as Darth Callidus, prove yourself worthy and one day you will rule everything you set your sights upon. You will become King… of all this."
"Yes, my Lord" announced Darth Callidus, standing "I will do everything in my power to honor my mother's, Estha Mereel's, memory and the honor of Clan Mereel and fight for the Emperor's glory. I will bring terror upon the Jedi and the Republic, this I swear as both a Sith and a Mandalorian!"
Ah, how proud his wife would have been to see her thirteen year old son reach Mandalorian adulthood and be ready to make his own way out into the Galaxy, Darth Marr would watch over his son with the help of Darth Decimus and they would look forwards to the results of Callidus's training. The secret of the Emperor's plan for Callidus however, would remain secret between Marr, and those that had been within that room all those years ago.