Shadow-of-Sundered-Star

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

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

The Didact was 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, and the one who eventually activated the Halo Array. Although he was physically killed by the former Master Builder Faber, he lived on by implanting his consciousness within a young Builder known as Bornstellar Makes Eternal Lasting. Though he believed in the mantle, he believed that the mantle should belong to the Forerunners alone and saw Humanity as a threat rather than the successors that most other Forerunners saw them as.

Warrior-Servant career
The Didact was a Promethean, a member of an extremely powerful class of Warrior-Servant. He gained his name while teaching at the College of Strategic Defense of the Mantle. On Charum Hakkor, he met a Lifeworker named the Librarian and married her. They had several children, who followed their father's footsteps and became Warrior-Servants. During the Human-Forerunner wars, the Didact lead the Forerunner military against the humans. Though all of his children died, the Forerunners were victorious. After the Charum Hakkor campaign, he and a group of Prometheans, including the Confirmer, discovered a stasis capsule on Charum Hakkor which contained the Timeless One, the last of the Precursors.

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. However, a faction of Builders lead by 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.

Discovery on Erde-Tyrene
In his exile, the Didact entered a state of meditation inside of a Cryptum, which was placed by the Librarian in Djamonkin Crater on Earth. 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.

During his subsequent travels with Bornstellar, the Didact performed a brevet mutation on the young Manipular to allow him access to the Domain. With the mutation, the Didact transferred all of his memories and knowledge to Bornstellar. The Didact was later executed at the hands of the Master Builder, making Bornstellar, for all intents and purposes, the reincarnation of the Didact. After surviving the Mendicant Bias' assault on the capital, the Didact would reunite with his wife, the Librarian on Installation 00 and resume his duties as supreme commander of Forerunner military due to the present threat of the Flood.

Forerunner-Flood war
"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, he 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 "Where it is safe". 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".

Return
"Time was your ally, human, but, now, it has abandoned you. The Forerunners have returned."

- The Didact to John-117, after his awakening.



In 2557, the Didact is awakened on Requiem when he tricked John-117 into releasing him by manipulating transmission signals from the UNSC Infinity, and leading him to the center of Requiem under the pretense that it was a transmission network when it was his Cryptum that sealed him within, and required a Reclaimer to activate it so he could leave it. Stating that Humans were not fit to uphold the Mantle, he calls the Librarian, 'meddlesome' in attempting to protect humans and by simply waving his hand, regaining control of all the Prometheans; turning their Hardlights orange instead of blue, and the Storm Covenant, as he dismisses John and Cortana.

The Didact then uses his new-found forces to assault the grounded UNSC Infinity, however the UNSC forces aided by Master Chief are able to push back the assault and even drive the Didact's vessel away. The Didact then begins searching for "The Composer ", a weapon that can turn humans into Prometheans loyal to the Didact. Eventually, he learns it is located at Ivanoff Research Station orbiting Installation 03. Gathering his Covenant and Promethean forces, he departs Requiem for Installation 03, unaware that Master Chief and Cortana are stowed aboard a Lich. After arriving at his destination and fighting the UNSC forces there, the Didact is able to obtain the Composer and fires it at Ivanoff Station, instantly killing all UNSC personnel aboard, except Master Chief who, due to the Librarian's genetic manipulation, is immune to "Composing".

The Didact then departs for Earth to create a new Promethean army, but once again Master Chief follows him, this time aboard a Broadsword fighter hidden in Didact's ship. Upon arriving at Earth, the Didact is immediately attacked by a UNSC fleet led by Infinity. Coordinating with Infinity, Master Chief is able to make a hole in the Foreunner vessel's hull and board it.

Apparent Defeat
"So misguided. Humanity's imprisonment... is a kindness."

- The Didact's final words to John-117.

Master Chief eventually fights his way to the Didact; however he is too late to prevent the Didact from firing the Composer at Earth, specifically at the city of New Phoenix, which is instantly depopulated. Master Chief and the Didact engage in a brief battle, the Didact then claims that using the Composer on humanity to turn them into Prometheans is in truth 'a kindness' to them for destroying his people in the past. At which point Cortana and several of her clones manage to manifest themselves from the Hardlight bridge that the Didact was on and bind him to it and restrain Didact long enough for Chief to plant a Pulse Grenade on his chest. It detonates, wounding him and causing him to fall off the light bridge and into the Composer's energy below. Master Chief then destroys the Composer and the Didact's vessel with a Havok nuclear bomb as Cortana shields him from the blast with Hardlight, ultimately sacrificing herself.

Trivia

 * 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. Also, the conversation occurred after the Didact transferred his personality to Bornstellar, as Didact's original body was killed well before the war escalated to the activation of the Halo Array. Also, in the Iris campaign Server Episode 1, Didact's last words to the Librarian moments prior to the Array's activation can be read.
 * The title "Didact" is derived from 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. Though, given his appearance in Halo 4, it may have been Bornstellar who took on his mutation and memories.
 * Didact is the first Forerunner whose face is shown in the series.
 * Keith Szarabajka provides the voice for the Didact, also known for his performances as Harbinger in Mass Effect 2 and Joshua Grahm in Fallout: New Vegas' downloadable content Honest Hearts.
 * The Didact's physical appearance in Halo 4 is due to the fact that the Didact represented in the game is the Bornstellar-Didact, not the Ur-Didact. (his original form)
 * It is somewhat possible the Didact survived falling into the Composer's energy field, as he stated in the Terminals of Halo 4 that it "would not work" on his new form.
 * If one were to watch all the Halo 4 Terminals on Halo Waypoint, one would notice the number of fingers on the Didact's hands change from five in the first terminal to six in the last, corresponding with the mutations that the Forerunner Manipular known as Bornstellar Makes Eternal Lasting underwent to become the Bornstellar-Didact. In Halo: Cryptum, the Ur-Didact performed a brevet mutation on the young Forerunner; this transferred Ur-Didact's memories to Bornstellar in the process, esentially making Bornstellar a "reincarnation" of the Didact. This mutation caused Bornstellar's body to undergo various mutations, including his body build, the addition of an extra digit on each hand, etc.

List of appearances

 * Halo: Combat Evolved Anniversary
 * Halo 3
 * Halo 4 
 * Halo: Evolutions - Essential Tales of the Halo Universe
 * Soma the Painter
 * Forerunner Saga
 * Halo: Cryptum
 * Halo: Primordium
 * Halo Legends
 * Origins
 * Iris