Ur-Didact

"The peaceful one is at war without and within."

- The Mantle, Fifth Permutation of the Didact's Number

The Didact is a Forerunner Promethean who held an extremely high status in the Forerunner society as supreme commander of the entire Forerunner military. He wholeheartedly believed in the Mantle the Forerunners held to protect life, and initially opposed the Halo Array as a sin beyond measure. He was also the lover and husband of the Librarian.

Originally thought to have been physically killed by the former Master Builder Faber, the Didact effectively existed as two individuals during the final days of the Forerunner-Flood war; his original self, as well as his implanted consciousness within a young Forerunner known as Bornstellar Makes Eternal Lasting. To differentiate these two incarnations, the original Didact was referred to as the Ur-Didact, while his other incarnation was known as the Bornstellar-Didact. The Ur-Didact was eventually exiled on Requiem, not to be awakened until 2557, while the Bornstellar-Didact supposedly served until the final days of the Flood conflict; he was also the individual responsible for activating the Halo Array.

Warrior-Servant career
The Didact was a Promethean, a member of the highest and most powerful class of Warrior-Servant. Early on in his career, the Confirmer provided him a brevet mutation to a new form. He gained his name while teaching at the College of Strategic Defense of the Mantle; his students gave him the name because they found him to be a strict and demanding teacher. On Charum Hakkor, he met a Lifeworker named the Librarian and married her. They had several children, who followed in their father's footsteps and became Warrior-Servants.

During the Human-Forerunner War, the Didact led the Forerunner military against the humans. His method of carrying out campaigns in interstellar war involved a strategy referred to as "star-hopping", isolating and besieging points of strategic importance while ignoring any less significant targets. Though all of his children died in the war, the Forerunners were victorious; humanity was devolved and quarantined on their home planet of Erde-Tyrene, a fate which the Didact found to be just and fitting. After the Charum Hakkor campaign, he and a group of Prometheans, including the Confirmer, discovered a stasis capsule on Charum Hakkor which contained the Primordial, the last of the Precursors. After a brief exchange with the Primordial, the Didact sealed its timelock for nearly the next ten thousand years.

Following the end of the war and the first discovery of the Flood, he advocated a policy of vigilance and research in the event of a Flood resurgence. He also proposed the construction of shield worlds across the galaxy in order to monitor the galaxy for Flood outbreaks and provide military support should they occur; this strategy was to involve the characteristic star-hopping tactics he had utilized in the war with humankind. However, a faction of Builders led by Master Builder Faber proposed the construction of a series of superweapons to deal with the Flood instead, and they were successful in convincing the Council to sanction their plans. Having lost the political battle, the Didact was stripped of his power and forced into exile.

Revival and capture
In his exile, the Didact entered a state of meditation inside of a Cryptum, which was later placed by the Librarian in Djamonkin Crater on Earth. The war sphinxes containing the last essences of the Didact's children were placed to guard the Cryptum. Over one thousand years later, he was discovered and revived by a young Forerunner Manipular, Bornstellar Makes Eternal Lasting, who had come to Earth in search of Precursor relics. The Didact, while greatly displeased by his revival, deduced that it had to be the work of his wife. The Didact's awakening summoned a fleet of Forerunner ships in the area, but they were unable to pinpoint his precise location due to a baffler that cloaked the crater's central region. Instead of turning himself in, the Didact made a timely escape using a ship constructed from a design seed planted in the crater's central mountain by the Librarian, taking Bornstellar and the Manipular's human guides, Chakas and Riser, as well as his war sphinxes, with him.

Seeking to find out what had happened in his absence, the Didact set course for Charum Hakkor, where he discovered that one of the Master Builder's Halo installations had already been tested, eradicating all sentient life, as well as Precursor structures, in the system. Upon landing on Charum Hakkor, the Didact discovered that the Primordial had escaped from its timelock and was nowhere to be found. For Chakas and Riser, visiting Charum Hakkor stirred ancient memories which had been imprinted in their genetic material by the Librarian. Intending to trigger more of these memories, they traveled to the system where the San 'Shyuum, once humanity's allies, had been quarantined after their defeat by the Forerunners.

Before arriving in the San 'Shyuum home system, the Didact performed a brevet mutation on the young Manipular to allow him access to the Domain. With the mutation, the Didact transferred his consciousness, along with all of his memories and knowledge to Bornstellar, although they would not awaken within the Manipular until later on. Shortly afterward, they arrived in the San 'Shyuum system and met with the Confirmer, one of the Didact's Promethean comrades, on the Fortress-class vessel Deep Reverence, in order to gain access to the quarantined region of the system.

However, in orbit over Janjur Qom, the primary San 'Shyuum world, the Didact's ship was intercepted and dismantled by the Master Builder's forces who had been present in the system quelling a San 'Shyuum rebellion. The Didact and the others were taken prisoner; in the subsequent interrogations, the Didact refused to divulge information on the shield worlds or the control codes for the Contender-class ancillas. Although other Forerunners, including the Librarian, believed that the Didact had been executed, he had in fact merely been left to die in a Flood-infested system by the Master Builder.

Reincarnation
Believing the original Didact to be dead, the Didact's personality imprint in Bornstellar's body took full control of the Manipular, effectively making him a reincarnation of the Didact. After surviving the assault by Mendicant Bias on the capital, the Bornstellar-Didact reunited with the Librarian on the Greater Ark and resumed his duties as supreme commander of Forerunner military due to the present threat of the Flood.

Soon after, the Bornstellar-Didact tracked down the Halo installation carrying Mendicant Bias and the Captive from Charum Hakkor, as well as the humans who had accompanied him after his revival. His fleet intercepted the Halo ring, on a pre-determined collision course with a planet in a distant system. He proceeded to deactivate Mendicant Bias using his control codes and save the Halo and its research data on the Flood.

After the Halo had been successfully transported to the greater Ark, the Didact, accompanied by a wounded Chakas, interrogated the Captive, now imprisoned once again. Over the course of the exchange, the entity revealed the true nature of the relationship between the Precursors, the Flood as well as the Forerunners and humans, stating that the Forerunners were never meant to inherit the Mantle and that there was no cure for the Flood. Furious, the Didact then executed the creature by fully activating its slipspace stasis chamber, forcing it to live through a billion years in complete sensory isolation and causing it to decay to a state of total physical entropy.

Following his temporary victory, the Didact's power rose as he returned to the favor of the re-established Ecumene Council, also elevating the status of his wife. The debate on the Didact's plans for strategic solutions against the Flood was restored and the use of the Halos was delayed for a time.

The Composer
Toward the end of the Forerunner-Flood war, the Ur-Didact desperately struggled to come up with solutions to counter the effects of the Flood; one of these was mutating himself further to a new form. However, this failed to grant him immunity to the Flood, leaving only the Composer as a viable solution. While the Composer did not work on the Ur-Didact's new form, his warriors volunteered to be processed, transferring them from their biological forms to mechanical Promethean Knights, which would allow them to fight the Flood without risking infection. While these new warriors were highly efficient, the continued onslaught of the parasite led the Ur-Didact to consider other options to expand his army.

The Ur-Didact traveled to a Halo to which a population of humans had been transplanted, and used the Composer to digitize many of them. He considered this to be a just punishment for their past transgressions as a spacefaring species. The humans' minds were then used to create more Promethean Knights to bolster the Didact's forces. The Librarian saw this as an act of genocide and a severe violation of the Mantle, so she incapacitated him through force. She then placed her husband inside a Cryptum at the core of the Prometheans' shield world, Requiem. The Librarian sealed Requiem and took over the Promethean Knights stationed there, giving them orders to prevent the Ur-Didact from being reawakened.

Endgame
"Mendicant Bias is trying to prevent us from firing the Array. He speeds back to the Ark, but he won't succeed. Offensive Bias will stop him, and I will burn this stinking menace in your name. And then? I will begin our Great Journey without you, carrying this bitter record. Those who came after will know what we bought with this [false transcendence] - what you bought, and the price you paid."

- The Didact's final transmission.

Later on, during the war, the other Didact was constantly trying to convince the Librarian to give up on her mission to save other sentient life from the Halo Array's inevitable activation, and return to him to safety inside the Maginot Line. His pleas, however, were unsuccessful and the Librarian ended up destroying her own fleet, stranding herself on Earth to live out the rest of her days in a place she referred to as "Eden". After the Didact learned the Librarian's location, he prepared a rescue party to retrieve her. However, before they could depart, Mendicant Bias' fleet breached the Maginot Line and destroyed the rescue party. Stricken by grief, the Didact then activated the Halo Array, wiping out all sentient life in the galaxy and stating that he would begin "[their] Great Journey" without his wife.

Reawakening on Requiem
"I have long dreamt of this day, Reclaimer."

- The Didact

In July 2557, the wreckage of the UNSC frigate Forward Unto Dawn, carrying Spartan John-117 and his AI companion Cortana, arrived in the orbit of Requiem, where they were intercepted by a fleet of Covenant remnant warships. Though the Covenant had been denied access to Requiem's interior for three years, an entrance portal opened after scanning the Spartan and pulled all nearby ships inside. After landing, both the Spartan and the Covenant forces faced opposition from the occupying Promethean forces, until eventually discovering the Ur-Didact's Cryptum on what John and Cortana originally thought to be a communications relay satellite. Even in his imprisoned and hibernating state, the Ur-Didact appeared to be in partial control of Requiem's systems, being able to manipulate 's signal to lead John-117 to Requiem's core and release him, or hinder Cortana's attempts to access a local Cartographer.

Inadvertently awakened by John-117, the Ur-Didact easily disabled the Spartan with his powers and declared that humanity should not be allowed to reclaim the Mantle. Immediately after his revival, the Ur-Didact reassumed control of his Prometheans; the Covenant remnant forces present on Requiem soon joined forces with them against humanity. John and Cortana immediately recognized the danger posed by the Promethean and after the Infinity had crash-landed on Requiem, they attempted to convince Captain Del Rio of the Infinity to take more drastic action against the Ur-Didact before he regained his full strength. However, Del Rio instead opted that they leave Requiem as soon as possible, leaving John and an increasingly rampant Cortana facing the Didact by themselves. As the Master Chief persisted in his attempts to stop the Ur-Didact, the Promethean addressed the Spartan telepathically several times and gradually came to be greatly impressed by his opponent.

Attack on Earth
"Humanity's imprisonment is a kindness."

- The Ur-Didact to John-117 during their final confrontation.

The Didact, after being forced to retreat, left Requiem aboard his personal flagship, Mantle's Approach. He headed for Installation 03, where he successfully took control of the Composer and digitized everyone on Ivanoff Station aside from the Master Chief, who had been genetically augmented by the Librarian. The Ur-Didact then set course for Earth, intending to prevent humans from again threatening Forerunner dominance. However, the Master Chief boarded his ship with a HAVOK nuclear warhead, intending to destroy the ship from the inside. The Promethean general confronted him, but Cortana was able to hack into the system and use hard light strands to bind the Ur-Didact into a light bridge and immobilize him. The Chief then planted a grenade on the Ur-Didact, blowing him off the bridge and sending him falling into a slipspace rupture beneath the Composer. With little time left, the Chief detonated the fusion bomb and destroyed the ship, though Cortana, using the last of her power, was able to save him from the blast.

Personality and traits
"But what I would not give to have earned a single company of Prometheans here right now. They would most certainly restore order with their trademark lethality, although...that would mean he would have to be here, too. And without the Librarian around to temper his rage, well... These Reclaimers might almost prefer the Flood."

- 343 Guilty Spark before Installation 04's destruction, referring to the Didact.

As the leader of the Prometheans, the Didact is immensely experienced and powerful. Generally, he is stoic and calm, but quick to anger if provoked. The Didact adhered strictly to Warrior-Servant precepts and traditions, and fiercely opposed anything that clashed with his ideals. This was the reason for his opposition to the Halo Array, as he viewed it as an affront to everything the Mantle stood for. He was also a follower of the Warrior-Servants' interpretation of the Mantle, believing that defying the Forerunners was tantamount to defying the Mantle itself. In his view, however, the Mantle accepted everyone, even contemporary humanity who conquered other species, although this did not change his condemnation of such actions or the strong resentment he felt toward humanity.

The Didact rarely showed any fear, although he openly admitted to being afraid to confront the Primordial, due to what it represented and the potential implications it may have had on his deepest-held beliefs. The subsequent revelations shook him to the point that he was unable to contain his fury and executed the creature out of anger.

When first meeting with Bornstellar, the Didact viewed the Manipular as foolish and naive, cursing him for waking him from his hibernation, but over the course of their travels he would begin to share some of the wisdom gained as a result of his experience, effectively becoming a mentor figure to the young Forerunner. This continued even after the two had been separated, with the Didact's imprinted consciousness offering his view on various matters and making occasional wry comments to Bornstellar, until fully subsuming his consciousness in order to continue the original Didact's work.

Views on humanity
"Humans are naturally purists. They resent having to live with other species. In fact, they're among the most contentious, bigoted, self-centered... I never understood how my wife tolerated them."

- The Didact

The Didact was considered in his time to be the supreme enemy of humans, viewing mankind as a grave threat and considering them to be extremely contentious, bigoted and self-centered. However, in his own mind this animosity was not driven by hatred or malice; rather, it was a largely rational reaction to humanity's actions. His actions toward the end of the Forerunner-Flood War - specifically the use of the Composer to convert humans into digital intelligences - were born of desperation and thus less rational; the Librarian regarded these acts as horrific.

While dismissive of the potential for humans to take on the Mantle, he also respected humans as warriors and regarded them as honorable, unlike their San 'Shyuum allies who had surrendered earlier in the war. This was demonstrated when he met with his main opponent, Forthencho, the Lord of Admirals, in person after the humans' defeat, speaking to him as a fellow warrior and reassuring him about the future despite humanity's grim predicament. He also understood humanity's motives for aggressive expansion after studying their records of their struggle with the Flood. Nonetheless, he felt it necessary to eradicate the contemporary human civilization entirely to ensure they would not rise to challenge Forerunner dominance again.

The Didact's antipathy toward humans was at least partially curtailed by the Librarian, who was, in contrast, regarded as humanity's greatest protector. Despite his love for her, the Didact was incapable of understanding his wife's protectiveness toward humanity, and resented her efforts to keep humanity safe from his justice and retribution.

He appeared to regard Chakas and Riser, the two humans who accompanied Bornstellar, with relative indifference, viewing them as mere annoyances, although he tolerated them because they were part of his wife's plan. By the point the Bornstellar-Didact reunited with the two, he appears to have had more of sympathy for them; he trusted Chakas enough to connect with him to Installation 07's control interface and enlist his aid in saving the ring, and later treated Chakas and the other humans gently, expressing condolence for everything they had been forced to go through.

Abilities
As an immensely powerful Forerunner with incredibly advanced technologies at his disposal, the Didact has a number of extraordinary abilities. He has the capability to generate and control powerful constraint fields at will, in effect granting him the power of telekinesis to restrain or physically harm his opponents. This was demonstrated when he used this ability on John-117, immobilizing him and causing him to float helplessly in the air, before throwing him against a wall. Later, during the confrontation aboard his ship, he inflicted direct physical harm on the Spartan, who was only saved by Cortana's intervention.

He can also manipulate the architecture of areas under his control, such as within Requiem or his ship. For example, he disintegrated a wall John-117 was taking cover behind, and later manipulated the platforms inside a tower on Requiem to hinder the Master Chief's progress. He has direct control over his mechanical Promethean armies, and was capable of returning them to his command with a mere gesture. The Didact was also capable of speaking to John-117 via a form of telepathy after the latter received the Librarian's genetic modifications; whether this is an innate biological ability or one facilitated by technology remains unknown.

Physical description and appearance
A full-rate Promethean, the Didact is a physically imposing figure, easily towering over a fully-armored SPARTAN-II. In comparison to other Forerunners, he stood nearly twice a Manipular's height and weighed four or five times as much. He has massive, heavily muscled limbs and hands with six fingers, two of them being opposable thumbs; Bornstellar Makes Eternal Lasting believed that he could easily have crushed a human with his bare hands.

In his original form, his skin was grayish pink in color and he had patches of bluish white fur on the top of his head and shoulders, as was common with Warrior-Servants. He had strong, serious facial features and deep-set, gray eyes. The Bornstellar-Didact was mostly similar to the Ur-Didact in appearance and stature and had a "broad, grotesque face", although upon closer examination, his comparative physical youth was apparent in his appearance.

The new form assumed by the Didact near the end of the Forerunner-Flood war, caused by a failed attempt to decipher Flood immunity, was even larger than his original one and had a more grotesque, bestial appearance, with more pronounced facial features, much less prominent lips and the addition of large fangs. His eyes also became more deep-set and red as opposed to the original grayish blue, and his fur changed from pale blue to dark brown.

The Didact's personal armor worn after his most recent mutation has an uncharacteristically ornate appearance, in contrast to the more humble designs historically worn by Warrior-Servants. The suit is comprised of a number of silver armor sections with complex patterns of orange light. The bodysuit beneath the armor sections is colored black and dark red, resulting in an appearance similar to exposed musculature. The helmet of this armor suit appears to be modeled after a skull, with orange "eyes" rather than a visor like before, and a small breathing port on the nose. The original armor worn by the Didact was in line with traditional Warrior-Servant armor in both design and coloration; bearing the mottled gray and blue colors of a Warrior-Servant, the suit was, despite his lofty status, considered austere in contrast to more lavishly decorated armor worn by the Builders.

Trivia

 * The Didact is the main antagonist of Halo 4, in which he is voiced by Keith Szarabajka, and he will be a "pivotal character" in subsequent media. Voice actor was either cast or auditioned for the role of the Didact, and performed some of his lines, but the role was apparently recast after Pizzuto died in February 2012. Before the official confirmation that the Didact was to be the antagonist, a number of sources made several suggestions that this may be the case. The final terminal of Halo: Combat Evolved Anniversary contains a foreboding reference to the Didact's possible return, and there are hints throughout Halo: Primordium that humans are once again faced by the Didact; most prominently in the very end of the novel. A symbol very similar to that of the Didact's appears in the Halo 4 Cinematic Trailer, in which the icon is shown overtaking the 's monitors while a wave of orange light scans throughout the ship. The icon is later seen turning over in the end of the trailer, superimposed by the text "An ancient evil awakens," while an unknown voice is heard saying "I have long dreamt of this day, Reclaimer." Near the end of Origins, Part 1, the Didact's empty armor is seen being placed into storage by another Forerunner after the activation of the Array, with his body nowhere to be seen; however, as this is based on the semi-rampant Cortana's interpretation of the available data, it is possible that such an event never really occurred.
 * A centuries-long series of conversations between Didact and the Librarian can be found inside Forerunner terminals in Halo 3. When the terminals are accessed, the player is eventually moved to a conversation that was recorded before the Halo rings were fired but after he had transferred his consciousness into Bornstellar. The Didact's last words to the Librarian moments prior to the Array's activation are featured in the Iris campaign Server Episode 1.
 * The title Didact is a back-formation of the word didactic, which means to instruct others, especially with regard to morals. This is ironic because the Didact, who sought the dismantling of the Halo Array to protect the galaxy, ultimately activated the rings, defying his morals.

List of appearances

 * Iris
 * Halo 3
 * Terminals
 * Halo Legends
 * Origins
 * Halo: Evolutions - Essential Tales of the Halo Universe, Volume 1
 * Soma the Painter
 * Halo: Cryptum
 * Halo: Combat Evolved Anniversary
 * Terminals
 * Halo: Primordium
 * Halo: The Thursday War
 * Scanned
 * Halo 4: Forward Unto Dawn
 * Halo 4
 * Halo: Silentium