Darth Tenebrous

After being selected as an apprentice by a Twi'lek Sith Lord, Rugess Nome became Darth Tenebrous. Together, he and his master devoted themselves to the Grand Plan. In the mix, Darth Tenebrous constructed a red lightsaber during his Sith training, and would go on to wield the weapon when he either sparred or honed his lightsaber combat skills. One of the schemes Tenebrous and his Master devised was the development of a targeted virus that would sever the Jedi's connection to the Force; yet despite spending years developing the virus, the project was ultimately a failure.

Tenebrous eventually came to see the dark side of the Force not as a kind of malevolent mystic sentience bent on spreading suffering throughout the galaxy but as an energy source, which could, like any energy source, be manipulated. When Nome saw no further use for his master, he killed them.

Rugess Nome was widely known for creating legendary starship designs throughout the galaxy, whilst hiding his identity as a Sith Lord.

In searching for a Sith apprentice, Tenebrous manipulated a middle ranking InterGalactic Bank agent named Caar Damask into meeting his future wife, knowing that if they had a child, their offspring would be strong in the Force. When the expected child, Hego Damask, turned five, Nome traveled to Mygeeto and was able to convince his parents to hand him over. Tenebrous took the child as his apprentice, naming him Darth Plagueis.

As with many of his predecessors as Sith Lords, Tenebrous worked hard to expand the Sith's network of informants and agents that had started with Darth Bane. These agents were the Sith's eyes and ears in all corners of the galaxy, providing them with information but also with access to the highest circles of power in galactic politics. As such, he took up the public persona of Rugess Nome, a starship designer whose constructs were delivered only to the elite members of the rising powers of the galaxy. Among these influential beings, politicians were often found in conjunction with entrepreneurs, bankers, industrialists, and any other being possessing enough power that could eventually assist the Sith designs. Tenebrous's apprentice, Darth Plagueis, assisted his Master in these efforts in his public persona as Hego Damask, a wealthy financier who eventually set up his own financial lobbying group, Damask Holdings. As the son of the former head of the InterGalactic Banking Clan, Plagueis also inherited the remote moon of Sojourn, and the Gatherings that often occurred there under the stewardship of his father. Originally conceived as a retreat for the wealthy, Caar Damask had used these Gatherings as a means to bring together influential beings and allow them to forment secret agendas for both business and political ambitions. Under Plagueis, Tenebrous used the Gatherings to extend his own influence over the Republic and the galaxy.

Among the people Tenebrous brought into his web were the leaders of the rising Trade Federation, which began to have a great deal of influence over the outlying systems and even in the Galactic Senate. The Federation would eventually become one of Damask Holdings's most important clients. Also included in Tenebrous's plots was the Gran Protectorate, the representatives of the government of the fuel-rich planet Malastare. The Protectorate's Senator, Pax Teem, was considered by Tenebrous and Plagueis as a potential candidate they could manipulate into the position of Supreme Chancellor.

Tenebrous also tried to bring other beings into his circle of influence. Among them was a wealthy industrialist named Kerred Santhe. Desiring to bring Santhe into his circle, Tenebrous offered him exclusive rights for a Rugess Nome starship. However, Santhe outwitted Tenebrous and agents of Santhe Security successfully stole the blueprints, cutting Nome out of the deal altogether. Santhe used the success of the starship, once it had been manufactured, to expand his holdings by acquiring a controlling share of Sienar Technologies. Narro Sienar, the company's chief designer, was only able to keep his position by marrying his daughter to Santhe.

Seeing a way to have his revenge and gain the friendship of Narro Sienar, Tenebrous sent Plagueis to assassinate Kerred Santhe in his apprentice's first mission as an assassin.

In 67 BBY, Tenebrous and his apprentice, Plagueis, traveled to the planet Bal'demnic to investigate a lode of cortosis ore. However, their M-2 mining probe droid had been sabotaged by Subtext Mining, and ignited a pocket of lethane gas, causing a massive explosion. Though Tenebrous managed to contain the explosion, Plagueis saw the opportunity to kill his Master, collapsing the ceiling of the cavern on to Tenebrous. Dying, Tenebrous congratulated his apprentice on succeeding him. However, the rockfall had crushed the starship with which the two Sith had arrived, and Plagueis was effectively stranded in a place where he required an enviro-suit to survive. When he realized that his apprentice's desire to kill him had seriously endangered the continuation of the Sith, Tenebrous expressed disappointment in his pupil. Plagueis, angered by this, broke the Bith's neck. As the unconscious Nome slowly died, Plagueis utilized the Force to study microscopic changes in Tenebrous' body, observing the slow death of his neurons and midi-chlorians.

However, this was not the end of Tenebrous, who ensured the survival of his own consciousness into altered midi-chlorians—which he labeled maxi-chlorians. Those maxi-chlorians would then migrate not into the Force, but into Plagueis himself, the "diseased one." Not possessing a Bith's precision, Plagueis would never suspect Tenebrous' consciousness was inside his body, infecting cells with maxi-chlorians that would cut off the host of its Force-sensitivity. In order to fulfill his goals, Tenebrous sacrificed his ability to sense the motion of the future, something he no longer required since he already knew his future. Tenebrous' ultimate plan was to eventually possess the prophesied "Chosen One" using the power of essence transfer when they were still young and unable to resist, giving Tenebrous access to a body with a historic amount of midi-chlorians.

As his body died, Darth Tenebrous entered his apprentice's body and slipped into his cells. As the retrovirus propagated, the Bith gained access to Plagueis' powers of foresight. At that moment, he discovered and felt Plagueis' own death at the hands of his apprentice, which was only visible as a smear of darkness. That vision horrified him; Plagueis would die too soon, and Tenebrous would not fulfill his ultimate goal—seizing and becoming the Chosen One when he would appear.

Seeking an answer to understand Plagueis' complacent behavior, Tenebrous threw again his mind at the future, but could see nothing, as the retrovirus infected Plagueis' every cell; his apprentice was now robbed of his foresight power. Wholly giving himself to panic, Nome escaped Plagueis' body to think about a way out, only to discover his mummified remains. Time had passed, possibly decades or centuries, but the Sith Lord was unaware of it. He then wondered if his foresight, instead of being eliminated, had been twisted in upon itself, forcing him to endlessly relive his death, thus acquiring the coveted immortality, but not as he wanted. At that moment of realization, the Dark Lord wished he still had a mouth with which to scream.

After Plagueis killed his master, he obtained Darth Tenebrous's lightsaber and conducted investigations into those responsible for the sabotage of the probe after his Master's death. Though he did not ultimately discover the culprit, his interrogation of a group of representatives of Subtext Mining on Sojourn led him to Naboo after one of their number attempted to make amends by informing him of a vast plasma source on the planet. There Plagueis would discover a young Human named Palpatine, his future apprentice Darth Sidious and the very same dark vision that had terrified Tenebrous in the moments of his death. True to his vision, Palpatine would ultimately murder Plagueis and bring the Grand Plan to fruition as Emperor of the Galactic Empire.

Darth Tenebrous was a rationalist in his approach to the Force, which he believed to be nothing more than a very potent tool. Tenebrous had a fixation with comprehending and shaping the future, which his apprentice, Darth Plagueis, considered to be a product of his Bith intelligence, which was grounded in mathematics and computation. He even believed that the Sith Grand Plan could be achieved by mating the powers of the dark side with expert Bith science. Tenebrous felt that with the aid of sophisticated computers and future-casting formulas, the beings of the galaxy could be provided for and the Jedi Order would gradually dwindle and disappear. Tenebrous was fatalistic as to the Grand Plan's success, believing that the dark side's rise could be predicted, but not influenced or hurried by the Sith. Plagueis disagreed, however, believing visions of the future to be inherently clouded and unreliable, and that the Jedi Order had to be toppled and destroyed rather than left to wither. This difference in opinion ultimately precipitated Tenebrous' decision to train Darth Venamis to supplant Plagueis.

Despite his rationalist approach to the Force, Tenebrous covered his body in tattoos and body markings representing esoteric concepts, which Plagueis discovered shortly before his master's death.

Darth Tenebrous was very powerful in the Force, and a talented lightsaber duelist, a trait that he passed on to his secret apprentice, Darth Venamis. Tenebrous was also proficient in Force speed, using it to attempt to escape the cortosis mine and used the Force to shield himself and Plagueis from a bomb's explosion. He could also hold up heavy rocks with the Force, an impressive display of telekinesis, and could fire the rare form of red Force lightning. Moreover, Tenebrous had powerful precognitive abilities, able to foresee his own death, something even Darth Sidious and Darth Caedus were unable to do.

In addition, Tenebrous designed his own starship and invented his own retrovirus that could turn his midi-chlorians into maxi-chlorians, as he had great knowledge of the former, knowing which counted belayed great power.

The Sith Lord did not possess the "innate gift" of Sith sorcery, but felt Bith science was far more potent.

Darth Tenebrous's name was included in a 2006 blog entry by Leland Chee, the keeper of the Holocron continuity database, marking the character's first mention in Star Wars canon. Chee stated that Tenebrous's name may have been derived from the word "tenebrous," a word meaning dark, gloomy, or obscure. In 2008, author James Luceno indicated that if he were able to, he would choose "Darth Tenebrous" as the name of the first Sith to ever use the Darth title. Tenebrous appeared in Luceno's 2012 novel, Darth Plagueis, as the Master of Darth Plagueis. His birth name, Rugess Nome, also appeared.

When deciding Tenebrous's species, Luceno was seeking an existing intelligent and "brainy" species in Star Wars canon. The Bith species fit the bill, but Luceno found that he associated Bith with harmless jizz-playing bands rather than menacing Sith Lords. However, cognizant of the fact that many different personality types could be found in a single species, he ultimately said "what the heck."

• Book of Sith: Secrets from the Dark Side
• The Essential Reader's Companion