The Librarian's sigil.

The Librarian, referred to in some sources as the Lifeshaper, was an influential Forerunner individual during the Diluvial War. She was the head of the Lifeworkers, a rate associated with biology and medicine, and led the Conservation Measure to preserve galactic biodiversity in preparation for the Halo Array's firing. We largely know of her through her archived conversations with her husband, the Didact, presenting a tale of a couple kept apart by the Librarian's adamant conviction to her work as well as their philosophical differences over matters such as the Mantle and the ultimate necessity of the Array. Though garbled by generations of mistranslation, this narrative is also echoed by various records discovered by the Covenant.

Biography

The Librarian had an important role in the final plans associated with the Halo Array. While she saw the Array as a crime without measure, she also came to view it as the lesser of two evils next to the existential threat the Flood posed to cosmic biodiversity. To preserve that biodiversity, she and her Lifeworkers insisted that all facilities of the Array should include contingencies for the preservation of sentient life, in order to reseed biota after the galaxy was wiped clean of sentient life. The Librarian worked with the rings' architect, the Master Builder, to ensure both the inclusion of biosphere refugia, indexing protocols and Flood research facilities in hopes that a cure or immunity to the parasite may one day be found. This was the beginning of the centuries-long Conservation Measure. While most Forerunners retreated to the safety of the Jat-Krula sphere, the Librarian and the Lifeworkers ventured beyond the line at great personal risk, using Keyships to send life to the Ark via portals located in regional staging areas.

In the final days of the war, she came across a pristine world orbiting a orange-yellow star far beyond the protected boundary of the Line. Teeming with complex life including a particular genus of sapients, the planet immediately caught her interest more so than the countless others she had indexed. Calling it the "Cradle of Life", she believed it and its inhabitants may harbor answers to the Forerunners' own long-held mysteries, lamenting the irony that such a lost Eden would only be discovered at the end of their civilization. She had the planet's biota carefully indexed, and initiated the construction of one final gateway to the Ark. After the planet's indexed specimens had reached the Ark, she remotely destroyed all the Keyships under her command as a security measure, cutting off access to the Ark from the Flood - and herself. She spent her last days in the East African savanna, tending to a garden she had built.

The Librarian remained in contact with her husband throughout these final days. The Didact, unwilling to doom his wife to a certain death, dispatched a rescue party to bring her back to the Ark. However, the rescue party was destroyed by the rogue AI Mendicant Bias as it burrowed into the Line with the Flood's armada. Out of options, the Didact activated the Array from the Ark. The Librarian perished instantaneously as the pulse from the nearby Installation 04 struck Earth.

In the Covenant religion

Known in the Covenant common language as Nedrallith, the Librarian occupies a key place in the classical Covenant pantheon in a mother goddess-like role. Venerated universally as a protector of life, she is associated with mercy, new life and sometimes creativity. She is often known by the epithets Irinthar, the Preserver, Ejten'ruun, the Great Mother, and especially among certain Sangheili traditions as Ranath-Ifen, the Keeper of the Cycle. Many other appellations are also used in various contexts by different religious schools. In Covenant iconographic tradition, the Librarian's cynosure or devotion-image is a sleek ovoid carven with curvilinear lines, and the colors blue-green and lilac are associated with her.

The Librarian has been known to the Covenant since fairly early on from data aboard the Anodyne Spirit, which while less complete, partly overlaps with some of the Terminal dialogs. A minor record mentioning her and her role was discovered by the pre-Covenant Sangheili, though they did not have access to the broader context around her until some time into the Covenant. In Sangheili tradition, the Librarian was syncretized with Rfenn, the personification of death and rebirth from a pre-Forerunner religion, and many characteristics and cultural associations of Rfenn were conflated with the Librarian when Forerunner worship became universal. The discovery of the epic poem known as the Kandonom Codex would later shed further light as to her activities. The Covenant would also go on to discover various minor mentions of the Librarian in secondary and tertiary sources, indicating that she was an important individual indeed.

Since the Forerunner records available to the Covenant were largely corrupted and incomplete, her role in saving life from the rings somewhat mangled. The Librarian is sometimes, if not universally, credited with blessing the rings' divine wind with the ability to initiate the Great Journey for the faithful, whereas the dreaded Flood and those unworthy of the Path would be mercilessly purged. In the Covenant's "Diluvial Narrative" or the "Last Days of Creation", the Librarian's indexing efforts are rationalized as a way of preserving species who had not yet reached a sufficient state of enlightenment to join the Forerunners in their ascendance. Since the Rings' divine wind elevated the worthy while purging the profane, the still-primitive species that inhabited the galaxy had to be safeguarded from it so that they may find the Path themselves when they were ready. But even the Librarian could not save all of the galaxy's species, and so she chose to preserve only those she deemed most worthy of the Great Journey.

This is also one rationale for the Covenant's Doctrine of Universal Conversion: since the Librarian saw fit to preserve them, all sapient species alive in the galaxy since the Forerunners' departure and the "Great Purification" must have the innate potential to embark on the Journey. Though some interpretations argued that unworthy species may have been left as a test for the worthy or as a show of the Librarian's mercy, it was commonly assumed that she did not save species for no reason. This piece of dogma is why the Covenant generally did not take pride in wars of extermination, and sought to downplay the select few they had fought in their early history; this has been cited as one reason why the Human-Covenant War was so disruptive to the Covenant status quo.

Though the popularity of individual deity-worship has waned in the Covenant over the last millennium in favor of the Transcendental traditions pushed by High Charity's clergy, the Librarian is widely venerated across the Covenant. She is particularly popular among the lower classes such as the Unggoy, who often emphasize her qualities of mercy and care for all species and use her story as an example of how the Forerunners intended the Path to be broad. It is her story that the Prophets would often preach in their sermons when the Covenant's member species were fractious, so that they may be reminded of how the Forerunners had blessed all species. As the Covenant's most prominent female deity, she is also revered by various female organizations and religious orders, most prominently the Rennai monastics and other healers but also many female Sangheili in general; though those engaged in the arts and trade often favor the Master Builder instead, and tutors and the select female Sangheili involved in military logistics duties turn to the Didact the most.