Rule of Two/Legends

"Two there should be; no more, no less. One to embody power, the other to crave it."

- Darth Bane

The Rule of Two doctrine, also called the Banite system and known as Chwayatyun in Sith, was the guiding principle of the Order of the Sith Lords after the internecine New Sith Wars. It replaced the practices of Lord Kaan's Brotherhood of Darkness, which claimed equality among Sith Lords and forbade the use of the title "Darth".

The Rule of Two was instituted by Darth Bane, once a student at Kaan's Sith academy, in response to what he viewed as inevitable, self-destructive infighting within the Sith Order. The Rule of Two states that there would be only two Sith at one time, a Master and an Apprentice, guaranteeing that when the Apprentice becomes powerful enough in the ways of the dark side to take the title of Master, only then would they be worthy of the title. This transfer of power would only take place when the Apprentice takes their Master's life and finds a worthy student to repeat the cycle, this way the Sith will grow more powerful and still exist through the new Master. Both Master and Apprentice were considered to be Sith Lords.

The practice survived with varying levels of enforcement for a thousand years until the murder of Darth Tenebrous at the hands of his apprentice in 67 BBY&mdash; Darth Plagueis held the doctrine in contempt, and intended to live forever together with his own apprentice, Darth Sidious. Although the latter murdered his master in accordance with the Rule of Two and trained apprentices of his own, never more than one at the same time, he did not fully accept it, following instead his own Rule of One.

Creation
"When your power eclipses mine I will become expendable. This is the Rule of Two: one Master and one apprentice. When you are ready to claim the mantle of Dark Lord as your own, you must do so by eliminating me."

- Darth Bane, to Darth Zannah

In an attempt to avoid the seemingly inevitable clash between power hungry Sith, Darth Bane sought to reinvent the Sith Order with only two members&mdash;a Sith Master, and an Apprentice. Bane created the Rule of Two in a way which would prevent the Sith becoming like Kaan's Brotherhood of Darkness; Darth Bane thought the Brotherhood was weak and decided he must destroy it, then rebuild the Sith order as otherwise they were doomed to fail like all Sith before them. He decided there should only be one apprentice because if there were multiple the strongest would be held back by the weaker apprentices, this also prevented the weaker apprentices joining together to defeat the more powerful master leaving the master to be replaced by someone weaker. Bane decided "One Sith must contain all the power of the dark side. One Master must decide how that power should be used."

With no Master to keep the students in line, they would eventually turn on each other and kill for the power they had joined to take. No matter what the outcome, the new Master would still not be as strong as the last one. This process would then continue, leaving an even weaker Master than the previous one at the end of each cycle.

His course of action decided, Bane destroyed the Brotherhood of Darkness in true Sith fashion by duping Lord Skere Kaan into using a Force technique he learned from his studies of the dark arts known as the Thought bomb. Lord Kaan gathered together every Sith Lord in the Brotherhood as the Jedi were closing in to destroy them when he detonated the Thought bomb. Bane, knowing what would happen to Force-sensitive users within the bomb's range, escaped the Brotherhood's fate and hid from the surviving Jedi. Bane was then free to start his new Sith Order implementing the Rule of Two with his newfound apprentice, Zannah. Through his actions, Bane fulfilled the prophecy of the Sith'ari and ended the New Sith Wars.

For nearly 1,000 years, the Sith watched and waited, destabilizing the Galactic Republic whenever opportunity arose without revealing themselves. Around 188 BBY, during the Dark Jedi Conflict, Kibh Jeen warned the Jedi that the Sith had survived and were operating utilizing the Rule of Two, his warnings were mostly ignored or passed off as the rantings of a madman.

Prelude to the Empire
"Remember, the first and only reality of the Sith&hellip; there can only be two. And you are no longer my apprentice. You have been replaced."

- Darth Sidious, to Darth Maul

By the time of Rugess Nome/Darth Tenebrous, the Sith had come to the conclusion that the Rule of Two had essentially expired, as the time was coming when they would finally gain their revenge over the hated Jedi Order. However, this was always the opinion of the Master only, as the apprentice was invariably in the same subservient position as when the Rule was first envisioned.

During this 1,000 year period, the Bith Dark Lord of the Sith Darth Tenebrous emerged, taking a Muun, Darth Plagueis as his Sith apprentice. It is noted that Tenebrous broke the Rule of Two whilst training Plagueis, as he took a fellow Bith as an apprentice, dubbing him Darth Venamis. The mantle of Sith Master ultimately went to Plagueis, not Venamis, after Plagueis bested him in a duel. In 67 BBY, Plagueis killed his master on Bal'demnic, taking the title of Dark Lord of the Sith by 60 BBY, seven years later. Shortly after his ascension, the Muun took the human Palpatine as his apprentice, inducting him into the Order as Darth Sidious. Darth Sidious, under the guise of Senator Palpatine, was elected Supreme Chancellor in 32 BBY and masterminded a devastating galactic war involving the Republic, and, as Emperor of the newly formed Galactic Empire, brought the Galaxy under the control of the Sith, bringing about their foretold revenge.

Sidious broke the Rule of Two at least twice: once by training Darth Maul while still under the tutelage of Darth Plagueis; and secondly, by taking on two apprentices at once, and in the form of two Jedi: Count Dooku (former padawan of Master Yoda ), dubbed Darth Tyranus, and the Fosh Jedi Vergere. Vergere was said to be merely a candidate and not a "true" apprentice, and apparently left after discovering the depths of Palpatine's madness. In Maul's case, Plagueis had been informed of his existence and purpose by Sidious before Sidious began training him. With regard to Maul, Plagueis and Sidious had planned from the start for him to be nothing more than a disposable weapon and not a true Sith Lord. As such, neither Sidious nor Plagueis considered his existence to be a violation of the Rule, not even when Sidious bestowed the title of "Darth" upon him. It also appears that Sidious considered offering Dooku a place at his side prior to Maul's defeat, although details on the timing are vague and, as previously stated, Sidious did not consider Maul to be a true apprentice. In any case, Sidious secretly intended to create a new doctrine that ensured he was the permanent ruling Sith Lord, and that his apprentices would merely be useful tools rather than usurpers.

Darth Tyranus pledged to personally teach young Asajj Ventress in the ways of the dark side, and privately referred to her as “apprentice”, and she addressed him as “Master”. Dooku never bestowed the title of Darth to Ventress, perhaps out of respect for the Rule of Two. She certainly believed their master/apprentice status to be genuine,  and in any case it can be heralded as a sign of Tyranus’ rising ambitions. Sidious sensed a disturbance in the Force concerning Ventress. He considered her enough of a potential threat that he ordered Tyranus to eliminate her as a test of his continued loyalty. Tyranus acquiesced and, while disavowing Ventress as his apprentice, turned his fleet’s own guns on her at the Battle of Sullust. Erroneously giving Ventress up for dead, Tyranus soon after took Savage Opress as a new Sith apprentice with the ultimate goal of overthrowing Sidious and ruling the galaxy together, though that plan did not come to fruition either. Savage also never received a title of Darth.

Maul, after his narrowly surviving his duel with Obi-Wan Kenobi and faking his death, broke the Rule of Two as well. Shortly after returning from his exile and uniting with his brother, Maul declared himself Opress's master and demonstrated his superiority over Opress. He remarked that there could only be two&mdash;yet in his decision he had created two rival pairs of Sith. However Darth Sidious eventually corrected this oversight by searching them out and single-handedly defeating both in mortal combat, preserving the Rule of Two. Only Maul survived the battle; Sidious decided that his former apprentice could be of further use to him.

Imperial Period
Sidious and Darth Vader trained and employed a number of Dark Jedi and other Force-sensitive agents such as the Dark Acolytes, the Inquisitorius, and the Dark Side Elite. As these agents were not taught the secrets of the Sith and were considered merely acolytes, not apprentices, they did not consider this a violation of the Rule of Two. However, the fact that Tyranus sought to replace the Jedi Order with a Sith army, the so-called Fist of the Empire, indicated that he had envisioned the abolition of the Rule of Two once the Sith took over the galaxy.

Just as Sidious had taken Darth Maul as an apprentice before truly ascending to the rank of Master, Vader took it upon himself to train a secret apprentice of his own. Vader's physical and psychological traumas had diminished his potential in the Force, and he did not believe himself capable of overthrowing Sidious, the most powerful Sith Lord in history, alone. To that end, he endeavored to mentor an exceptionally powerful Force-wielder who would not only serve as his personal assassin, but would one day stand with him to overthrow Sidious. Thus for several years, Galen Marek, codenamed Starkiller, was trained in the ways of the Sith and the dark side of the Force. Marek became a merciless assassin, devoted to the goal of destroying Sidious in order to become a true Sith Lord. Vader later changed his mind about using Marek to overthrow Sidious and attempted to kill him. Marek survived, and went on not only to redeem himself, but to provide the impetus for the formation of the Rebel Alliance.

Despite Marek's unanticipated redemption and subsequent death, Vader refused to lose an extremely powerful asset and resorted to relying on the cloning technology of Kamino, and thus continued to violate the Rule of Two by creating a clone of Marek to replace his former apprentice. After many failed experiments, including a rogue clone who escaped from the Timira City Cloning Facility, Vader succeeded in achieving his goal by creating a perfect clone who wielded all of Marek's strengths, but none of his weaknesses.

Despite all of the strengths of the Rule of Two, Bane overlooked two critical weaknesses in his philosophy.The first, and the one of most concern to Bane, was the possibility the Master might spend most of their lifetime training an unworthy apprentice. Later in his life, Bane believed this to be the case with his apprentice Zannah. Aging poorly due to a lifetime of immersion in the dark side, and with Zannah apparently content to toil in his shadow, Bane desperately sought out the secrets to eternal life in order to buy himself enough time to train a truly worthy apprentice. His fears for Zannah came to naught, as she had in fact been preparing to kill him even as he had begun to worry that she was simply waiting for him to age to the point where he would be an easy kill. Zannah proved herself worthy by dueling and very narrowly defeating Bane on Ambria, and continued the Rule with an apprentice of her own. The possibility of training a failed apprentice would go on to irk other Sith Masters like Darth Cognus, whose first apprentice left her over idealogical differences. Additionally, despite very the inspiration for the Rule of Two, Revan, renouncing the dark side and killing the reigning Sith Lord, Darth Bane overlooked another critical weakness in his Rule&mdash;that one of the Sith Lords may be redeemed and kill the other. When Anakin Skywalker killed Darth Sidious in a selfless act of sacrifice, he redeemed himself of the life he lived as Darth Vader. Without Sidious or Vader, the Order of the Sith Lords was effectively dissolved since its only two members were dead. Thus, it appeared that there were no others to carry on the Order's traditions and teachings, and the Rule of Two was veritably destroyed.

Lumiya, one of Vader's secret apprentices, declared herself Dark Lady of the Sith and established her own Sith Order. She remained faithful to Darth Bane's ancient diktat, the Rule of Two, by taking Flint as her first apprentice, and then Carnor Jax. Her third and final apprentice was Darth Caedus, the grandson of Darth Vader and formerly known as Jacen Solo. Before her death, she instructed Caedus to find an apprentice for himself. He fulfilled her last wish after finding a suitable apprentice in Tahiri Veila, a fallen Jedi Knight whose emotional attachment to Caedus's dead brother brought about her fall to the dark side. However, Caedus's death, alongside Veila's turning back to the light side shortly beforehand, brought an end to the Rule of Two for good.

Abandonment
By the year 130 ABY, a new Sith Order emerged under the leadership of Darth Krayt, thus taking the place of the former Order of the Sith Lords. Unlike Bane's Order, Krayt abolished the Rule of Two and replaced it with the Rule of One, with one Dark Lord of the Sith representing the Order itself, while also commanding many Lords, acolytes, and minions.

His revision of the Sith was met with extreme disapproval and outrage, particularly from the gatekeeper of Darth Bane's holocron. When Krayt sought the wisdom of the ancient Sith Lords, they rebuffed him as an offensive heretic and a false Sith. Darth Nihilus did not provide Krayt with helpful information, Darth Andeddu accused him of heresy, and Darth Bane warned the Rule of One would be the death of Krayt and the entire Sith.

Surviving Adherents
By 138 ABY, at least one Sith still believed in the philosophy of the Rule of Two, and ended up wiping out the One Sith to re-establish it. However, this ironically led to the presumed extinction of the Sith as a whole, as his attempt at procuring an apprentice failed, with him dying at the hands of Ania Solo.

Behind the scenes
Chronologically, Darth Rivan predates Darth Bane, yet one of the traps in Darth Rivan's fortress, as shown in A Mon Alone, is based on the Sith adherence to the Rule of Two. However, Rivan did not pre-date Darth Revan, and in fact based his name off of the historical texts of Revan, whose teachings about apprentices inspired Darth Bane to implement the Rule of Two.

On Hypori around 54 BBY, Darth Plagueis said to his apprentice Darth Sidious that rather than the tens of thousands of Jedi, only thirty in a millennium were fit to be Sith, implying that the Rule of Two spanned at least 30 individuals, including or up until him and his apprentice.

Known Rule of Two Sith

 * Darth Bane
 * Darth Zannah
 * Darth Cognus
 * Darth Millennial
 * Darth Vectivus
 * Darth Gravid
 * Darth Gean
 * Darth Ramage
 * Darth Tenebrous
 * Darth Plagueis
 * Darth Sidious