Rule of Two

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

- Darth Bane

The Rule of Two was a Sith philosophy mandating that only two Sith Lords could exist at any given time: a master to represent the power of the dark side of the Force, and an apprentice to train under the master and one day fulfill their role. The philosophy of two governed the Lords of the Sith for a millennium, beginning with its founder Darth Bane.

Creation
"Created the Rule of Two, you did."

- Yoda, to the specter of Darth Bane

Even before Darth Bane created the rule, the Sith doctrines still rotated somewhat around the idea of two: a master and an apprentice. Some Sith temples could only be entered by a pair of Force-users. The masters demanded loyalty from their apprentices, but they sometimes betrayed them if they found one with more potential.

Eventually, Darth Bane became the sole survivor of a war against the Jedi Order a millennium before the Clone Wars. Recognizing that it was Sith greed and in-fighting that led to their destruction, Bane created the Rule of Two, so the Sith could operate in secret, using subterfuge to plot their revenge against the Jedi. Bane developed the philosophy after his personal experiences and by studying ancient Sith documents. Bane thought that this new principle would prevent the power of the dark side from destroying the Sith Order once more and restructure the Sith in order to control internal struggles for power. To keep alive the Sith lineage, the apprentice had to slay the master to gain the title and take on their own apprentice, though they could die in the attempt and be replaced. This caused the relationship between the master and apprentice to not be one of trust, as both constantly searched for signs of weakness in the other.

Bane took an apprentice of his own and passed on his knowledge while establishing the new Sith way of pursuing power and revenge against the Jedi through manipulation and subterfuge. The Jedi became aware of Bane's philosophy and Bane was defeated. Although historical records weren't accurate, it was considered possible that Bane was killed by his own apprentice. Anyway, the Jedi went to falsely believe that they had destroyed the Sith forever. However, Bane's plans continued through his apprentice, allowing the Sith to survive secretly for years while planning their revenge against the Jedi Order. Rumors, neverthless, remained that the Sith were continuing in the shadows.

Plagueis and Sidious
"Unfortunately, he taught his apprentice everything he knew. Then his apprentice killed him in his sleep."

- Darth Sidious, remembering Darth Plagueis

The Sith carried out their vendetta for a thousand years, gaining power in secret while the Jedi still believed that the Sith had been destroyed. During this period, the Dark Lord of the Sith Darth Plagueis took Darth Sidious, the Sith persona of Senator Sheev Palpatine of Naboo, as his apprentice. They worked for years to coax the final secrets from the dark side of the Force. Sidious called back on the wisdom of Plagueis as a planner and a prophet, knowing full well that two Sith were required to enact their means; one to serve as bait for the dark side, the other to be the vessel. Success would allow them the ability to harness the full power of the dark side and rule immortal for ten thousand years.

Sidious and Maul
"Always two there are; no more, no less. A master and an apprentice."

- Yoda

While training under Plagueis, Sidious acquired a Dathomirian Zabrak named Maul as his pupil. He had initially considered Mother Talzin, Maul's mother, to be his Sith apprentice, but took Maul upon realizing his potential. Seeing no further use for his master, Sidious killed Plagueis in his sleep.

After killing his first Jedi, the Twi'lek Padawan Eldra Kaitis, Maul reflected that she would have made a good Sith apprentice, but that he had to finish her off to prevent his master from discovering his intended betrayal. Concurrently, Xev Xrexus from the Xrexus Cartel theorized the Sith's comeback, leading Maul to kill her as Sidious threatened him with death if they were prematurely discovered.

In 32 BBY, during the Invasion of Naboo by the Trade Federation, the Sith finally revealed themselves to the Jedi with Sidious sending Maul to Tatooine to capture Queen Padmé Amidala and take her back to Naboo so she could sign a peace treaty. The Jedi Qui-Gon Jinn faced Maul but was able to leave Tatooine with Amidala and his allies, realizing that the Sith had returned. During the Battle of Naboo, which broke the Federation's blockade, Maul killed Jinn only to be seemingly killed in turn by Padawan Obi-Wan Kenobi, leading the Jedi to realize the return of the Sith.

Sidious and Tyranus
"Remember, the first and only reality of the Sith. There can only be two. And you are no longer my apprentice. You have been replaced."

- Darth Sidious, to Darth Maul

With Maul gone, Sidious took the former Jedi Master Count Dooku from House Serenno as his next apprentice and bestowed him the name Darth Tyranus. During a mission on Sullust, Dooku considered recruiting the Jedi Knight Jak'zin as an ally to the Sith cause, but ultimately stopped when Sidious stated that a Sith Master needed only one apprentice and threatened to replace him with the Togorian Jedi. During the next decade, Dooku aided his master in engineering the Clone Wars, including orchestrating Jedi Master Sifo-Dyas' death, and then to use his name to order an army of clones to be created for the Republic and selecting bounty hunter Jango Fett as the genetic template for the clones. In 22 BBY, with the Confederacy of Independent Systems on their side, Dooku revealed his new allegiance to the Jedi and the Clone Wars began with the Battle of Geonosis.

The Rule of Two was violated by Dooku, who took the Dathomirian Nightsister Asajj Ventress on as an assassin and apprentice. However, Sidious, believing Dooku may have been training her to destroy him and sensing that her power had grown, ordered Dooku to eliminate her. Dooku obeyed his master and left her for dead following the Battle of Sullust. Dooku later took the Zabrak Savage Opress, brother of Maul, as his apprentice only for his plan to fail due to Ventress' intervention. Upon receiving a premonition of events to come, the Besalisk Jedi Master Pong Krell fell to the dark side in an attempt to become Dooku's new apprentice, but the clone Dogma executed him after Krell turned on the 501st Legion. Maul later revealed himself to be alive and took Opress as his apprentice, making two rival pairs of Sith. However, Sidious tracked them down and killed Opress during the Mandalorian civil war, whilst allowing Maul to live as he had other uses for him. Dooku took the Jedi Master Quinlan Vos as his apprentice after capturing him, but his plan failed again as Ventress gave her life to save Vos.

Sidious and Vader
"I pledge myself to your teachings. To the ways of the Sith." "Good. Good. The Force is strong with you. A powerful Sith you will become. Henceforth, you shall be known as Darth&hellip;Vader."

- Darth Sidious turning Anakin Skywalker into Darth Vader

In 19 BBY, shortly before the end of the Clone Wars, General Grievous kidnapped Palpatine, leading Kenobi and Anakin Skywalker to be dispatched to rescue him aboard the Invisible Hand. During a lightsaber duel aboard the ship, Skywalker killed Dooku before the trio eventually made it back to Coruscant escaping. Studentless again, Sidious seduced Skywalker to the dark side by telling him about Plagueis upon discovering his fears that Amidala, his secret wife, would die in childbirth. Skywalker initially revealed Palpatine's secret to Mace Windu, who then attempted to arrest the Chancellor. Skywalker, however, was forced to turn on the Jedi to save Palpatine from being killed.

No longer a Jedi, Skywalker became Sidious' final apprentice, who bestowed him the name Darth Vader. Sidious issued the order for clone troopers to turn against their Jedi Generals and Skywalker was sent to the Jedi Temple to kill the Jedi there. Afterwards, Skywalker travelled to Mustafar where he slaughtered the Separatist Council whilst Palpatine proclaimed himself Emperor and reorganized the Republic into the First Galactic Empire. After the failure of Yoda and Kenobi to finish off Sidious and Vader, Sidious saved Vader from dying on Mustafar and encased him in armor. Vader was then informed that Amidala had died due to his wrath. With his only loved one gone, Vader came to accept the reality and fully committed himself to the Sith.

Dark side adepts and cyborgs
"They are abominations. This is heresy." "You forget who is master and who is student. It is your duty to learn what I know. It is my duty to learn what there is to teach."

- Darth Vader and Darth Sidious

During the Imperial Era, Vader taught the Inquisitorius, a group of former Jedi who had turned to the dark side, and were tasked with hunting down the remaining Jedi, though the Inquisitors themselves only served the Sith and were not considered Sith apprentices, being mere dark side adepts. By 0 BBY, the Inquisitorius had ceased to exist.

Though seemingly invincible, the New Order was put in danger when the Alliance to Restore the Republic succeeded in destroying the Death Star battle station. Doubting Vader's capacities, Sidious accepted Doctor Cylo's suggestions in relegating Vader to a ceremonial apprentice and replacing him with a new biologically engineered one. When Vader met Cylo's creations, Commander Karbin, Tulon Voidgazer, twins Morit and Aiolin Astarte and a Trandoshan; he became confused. Vader, however, eventually proved himself to his master and killed each of Cylo's creations and Cylo himself.

Vader's conspiracy
"There is no escape. Don't make me destroy you. You do not yet realize your importance. You have only begun to discover your power. Join me and I will complete your training. With our combined strength, we can end this destructive conflict and bring order to the galaxy." "I'll never join you!"

- Darth Vader and Luke Skywalker about overthrowing the Emperor

Unknown to Sidious, however, Vader had already plans to dispose of him and taking Luke Skywalker, his secret son and the pilot who destroyed the Death Star, to join him and rule the galaxy. While trying to recover the Emperor's respect before Cylo's death, Vader became aware of his parenthood after the bounty hunter Boba Fett discovered the pilot's name and informed Vader of this. Focused on trying to get his son to join him the dark side, Vader killed Karbin and prevented Luke from being captured on Vrogas Vas. In 3 ABY, following the Battle of Hoth, Vader communicated with Palpatine aboard the Executor, as the Emperor had sensed the threat Skywalker posed to the Sith. Promising his master that Luke would choose over joining them or die, Vader managed to capture the crew of the Millennium Falcon on Cloud City and manipulated Luke into saving his friends.

Upon arriving on Cloud City, Bespin, Luke was unable to hear Leia Organa's warnings that Vader had set up a trap for him. Luke found Vader and the two engaged in a duel. Vader was able to defeat and cut off one of his hands before telling him that he was his father. Vader offered Luke the chance to join him and overthrow the Emperor and bring order to the galaxy. Luke refused and plunged himself into the shaft only to be rescued by the Falcon.

End of the Sith
"I'm looking forward to completing your training. In time you will call me Master." "You're gravely mistaken. You won't convert me as you did my father."

- Darth Sidious and Luke Skywalker, before the Sith's ultimate defeat

One year later, both the Empire and the Rebel Alliance were preparing for a definitive showdown above the Forest Moon of Endor with the second Death Star's superlaser finally operational. Still determined to find his son, Vader was sent by his master to Endor to wait for Luke to come to him. After Luke turned himself over to Vader, Luke attempted to turn Vader back to the light side of the Force. Vader refused his son's pleas and the two traveled to the Death Star where Sidious awaited.

Once in the Emperor's Throne Room, the Emperor welcomed Skywalker, promising to complete his training. Eventually a duel broke out between Luke and Vader, ending with Luke cutting off his father's hand. The Emperor prompted Luke to kill his father and take his place at the Emperor's side. Luke refused, stating he was a Jedi like his father before him.

Legacy
"Your show of power is impressive, but that cave had stood for thousands of years." "The past is the past." "I hoped to bring other apprentices to it." "You won't need other apprentices."

- Supreme Leader Snoke and Kylo Ren, during one of Ren's training sessions

Thirty years after the defeat of the Sith, Supreme Leader Snoke was deposed by his apprentice, the dark warrior Kylo Ren, in an act worthy of the Rule of Two.