Shadow-of-Sundered-Star (Earth-4001)

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

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

The Didact, born Shadow-of-Sundered-Star, is a Forerunner Promethean who held an extremely high status in the Forerunner society as protector of the ecumene, head of the Warrior-Servant rate and supreme commander of the entire Forerunner military. He wholeheartedly believed in the Mantle the Forerunners held to protect life, and fervently opposed the Halo Array as a sin beyond measure. He was also the lover and husband of the Librarian.

Originally thought to have been killed by the 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 IsoDidact. The Ur-Didact was eventually exiled on Requiem, while the IsoDidact served until the final days of the Flood conflict and was responsible for activating the Halo Array.

History
The history of the Ur-Didact is the same as his mainstream counterpart up until the end of the Human-Covenant War in March 2553.

Personality & Traits
The Didact was a highly experienced and powerful warrior, a result of his millennia-long career as a Promethean. Before his corruption by the Gravemind, the Didact was a noble and sensible figure. He 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 the weapons as an affront to everything the Mantle stood for. He was a follower of the Warrior-Servants' interpretation of the Mantle, believing that defying the Forerunners was to show contempt for the Mantle itself. While he believed that the Mantle accepted everyone, even contemporary humanity who conquered other species, this did not change his condemnation of such actions or the strong resentment he felt toward humanity. Although he generally demonstrated a stoic and calm disposition, the Didact could also be quick to anger if provoked.

After encountering the Gravemind, the Didact underwent a drastic shift in his personality. He became much less rational, his psyche distorting to the point of insanity. As part of its ploy to turn the Didact against his former allies, the Gravemind took advantage of his existing motivations, convictions and prejudices, most notably his opposition to the Halos and antipathy toward humanity, making these characteristics significantly more pronounced. Developing a belief in absolute, unconditional Forerunner supremacy, he concluded that the early Forerunners' violent seizing of the Mantle from the Precursors had been justified and that the Forerunners should mercilessly eliminate any species who might challenge their dominance in the future. He began to desperately pursue brutal and unrealistic strategies, such as creating his army of Promethean Knights, an obsession which eventually drove him to composing Omega Halo's human population; the irrational cruelty of this act finally convinced the Librarian to imprison him. While the Didact believed that his schemes would bring about a new age of primacy for the Forerunners, in actuality he was only working to the Flood's advantage by generating additional suffering and chaos.

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 as the IsoDidact. By the time the two reunited years later, their relationship quickly became much less amicable, in particular due to the IsoDidact's acceptance of the Halo Array as a final option.

Views on Humanity
The Didact was considered in his time to be the supreme enemy of humans, viewing mankind as a grave threat to Forerunner peace 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. After his encounter with the Gravemind, his attitudes became much more extreme and he opted to wipe out humanity entirely as a potential threat to the Forerunners' supremacy. This new stance, combined with his desperation to stop the Flood, was behind his heinous actions toward the end of the Forerunner-Flood war.

Prior to his transformation, while dismissive of the potential for humans to take on the Mantle, the Didact also respected humans as warriors and regarded them as honorable, unlike their San'Shyuum allies who had surrendered earlier in the war. In fact, he regarded them as the second greatest military power in the galaxy at the time. His respect for the humans 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. Furthermore, prior to being imprisoned after his fall from grace in the Ecumene Council, he stated that had the humans repented for their crimes, they would've been a civilization worthy of joining their own. The Ur-Didact appeared to regard Chakas and Riser, the two humans who accompanied Bornstellar, with relative indifference, viewing them as mere annoyances, though he tolerated them because they were part of his wife's plan and because he likely recognized the value of their personality imprints. Though disgusted to see Chakas as he looked too much like the humans who had nearly destroyed his fleets and murdered his children, the Didact was pleased to see Riser, a Florian. The Didact commented that he had specifically requested that the Librarian save the Florians because he saw them as peaceful yet full of cleverness. However, the Didact made it clear that this just made them worthy pets to him.

While he understood humanity's motives for aggressive expansion after studying their records of their struggle with the Flood, the Didact agreed with the Old Council's decision to eradicate the contemporary human civilization and banish the remnants of the species to their homeworld, as he felt that the humans had wrongly taken the Mantle upon themselves in their attempts to contain the Flood. The Didact also held that the Forerunners were more deserving of the Mantle than humans because of the latter's propensity for finding objects of worship in nature and in Precursor artifacts, whereas the Forerunners had always derived their beliefs solely from the Mantle.

The Didact's antipathy toward humans was at least partially curtailed by the Librarian, who was, in stark 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 the humans safe from his justice and retribution.

Technological Capabilities
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 manipulate powerful constraint fields at will, in effect granting him the power of telekinesis to restrain or physically harm his opponents from a distance. The Didact was also capable of generating a shockwave by stomping on the ground. He can also psionically transmit his thoughts into another organic being's mind and generate powerful linear energy blast.

The Didact possesses extraordinary neurological, mental and physical abilities bestowed by his senior Promethean form. One of these is the augmented state of perception known as "battle mode," splintering his perception of reality into several variable frames of reference with a slowed-down experience of time, granting him impressive multitasking abilities. The Didact is also capable of superhuman reflexes and strength. During large-scale engagements, the Didact would also tap into the sensory input of thousands of his fellow Prometheans simultaneously and experience the battle from their respective viewpoints in addition to his own. His memory is also incredibly accurate; while stranded on the Builder hulk in the Burn, he was capable of reciting a verbal control code comprising 400 random nonsense words and non-integral numbers after thousands of years and without the aid of an ancilla. After undergoing an experimental mutation in an attempt to become immune to the Flood, the Didact gained a new form that, while still susceptible to Flood infection, was no longer compatible with the Composer, thereby preventing him from joining his fellow Prometheans as a machine and allowing him to willingly levitate himself within a Composer's active beam without being affected at all.

Like Warrior-Servant armor in general, the Didact's personal armor was designed to attune itself to enemy weaponry.

The Didact can also manipulate the architecture of areas under his control, such as within Requiem or his ship.

Trivia

 * A centuries-long series of conversations between the Didact and the Librarian can be found in 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. The Didact's last words to the Librarian]] moments prior to the Array's activation are featured in the Iris campaign Server Episode 1. However, as later revealed in The Forerunner Saga and Halo 4, the Didact in the terminals is actually the IsoDidact as opposed to the Ur-Didact, as the latter had already been imprisoned by the time the rings were fired.
 * The title Didact is a back-formation of the word didactic, which means to instruct others, especially with regard to morals. In Halo: Cryptum, the title is established to have originated from his tenure as a teacher in the Forerunners' War College. His title also coincides with the responsibility the Librarian planned for him once he would awaken from his meditation, teaching and instructing humanity about the Mantle.
 * The "Ur" prefix means "proto-" or "original" in German, alluding to him being the original incarnation of the Didact.
 * In his entire military career he was captured three times.