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The Builders, referred to in some formal contexts as the Builder Corps, were the highest rate of the Forerunners, considered to be the most powerful in terms of intelligence, wealth, and political power. As their name suggests, the Builders were responsible for designing and constructing the majority of the Forerunners' advanced technology, including ships, weapons and the myriad of technologically advanced structures and objects seen throughout the Milky Way galaxy, most notably the Halo Array. The chief of the Builder rate and all its guilds was known as the Master Builder. The last Forerunner to hold this title was Faber.
In an archetypal sense, many Builders demonstrated an economically motivated and ambitious mentality, marked by a constant pursuit for more wealth and power. Certain Builder families, such as that of Bornstellar Makes Eternal Lasting, were so wealthy they could own entire planets for their personal use. One such world was covered in megascale architecture that served as a testament to their owners' engineering skill and power.
Builders were drawn to the Forerunners' ancient past, with some believing that Forerunners had long earlier possessed superior technologies and sought to recreate this past greatness with their technological achievements. Such beliefs were also the basis of elements in the rituals of the secret societies that existed within the Builder rate; these rituals had traces of the Forerunners' past beyond their recorded history, including symbols based upon the designs of ten-million-year-old warships which had otherwise been long forgotten. As Manipulars, Builders memorized the names of their ancestors, going back millions of years; these would be recited as part of a prayer meant to be spoken when faced with certain death.
The Builders' gained and maintained their prominence via technological innovations, such as the production of new weapons during major conflicts, though some Builders resorted to clandestine scheming and political machinations to achieve their goals. This aspect of the Builder rate became particularly notorious after Faber gained control of the Old Council and ruthlessly eliminated all of his opposition in positions of power, his corruption encompassing even the legal Juridical rate. Faber's rule also marked a difficult time for Builders who were not part of his cabal, and especially those who openly disagreed with his policies. The Master Builder was not beyond having dissenting voices removed by his loyal Builder Security forces, or formally prosecuted by the corrupt Juridicals.
At the height of their power, Builders held a monopoly on the accepted facts about Precursors' neural physics technology. In lectures mandatory to the other rates, including Lifeworkers, Builders dogmatically asserted that the star roads and other constructs were in fact fully inanimate despite their curious self-adjusting capabilities.
Builder Security was an organization of Builders who conducted security and combat matters. Many members of Builder Security were former Warrior-Servants who migrated into the Builder rate after the Warrior rate was diminished in the wake of Faber's takeover of the Old Council and the Didact's exile.
Builder forms were generally tall and slender and were considered more refined and sophisticated in appearance than Warrior-Servants. Consistent with their elevated position, Builders wore the most ostentatious style of armor of all rates; even the armor of a Builder Manipular was more opulent in design than that of a Promethean.
Builders achieved their power early in Forerunner history. The Builders, along with Warriors, played a part in the early suppression of the truth about the relationship between the Forerunners and the Precursors. Over a million years before the emergence of the Flood, after a Theoretical known as Boundless persisted in her studies of this aspect of the Forerunners' past, Boundless was silenced and the Theoretical rate was forcibly absorbed into the Builders.
During one of the Forerunners' civil wars over 500,000 years before the Forerunner-Flood war, the Builders purged the other rates of their ancient rituals while retaining their own. The Builders' power continued to accumulate during the millennium-long human-Forerunner wars, as they supplied the weapons. Toward the end of the wars, the Builders kept producing more weapons and ships than were ultimately necessary, further consolidating their political power and gradually transforming the attitudes of the Old Council itself. The Forerunners' ancient ways of understanding and enlightenment gave way for a more aggressive and ruthless general mentality, which also contributed to humanity's harsh punishment after the conclusion of the wars.
Following the end of the wars, the Builders, led by Master Builder Faber, designed a new form of superweapon known as Halo in preparation for the Flood's inevitable return. This plan was opposed by the Didact and the Prometheans, who instead proposed the construction of numerous shield worlds as a strategy to combat the Flood. The Prometheans lost this political conflict after several millennia, leaving the Master Builder effectively in total control of the Council and making him the most powerful Forerunner in the ecumene. While Faber lost his status for several years near the end of the Flood war, he would be restored in command by the remains of the New Council in the endgame of the conflict, not long before he met his end during the Flood's attack on the greater Ark.
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