Librarian

The Librarian, referred to in some sources as the Lifeshaper, was an influential Forerunner individual. 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.

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, the planet immediately caught her interest more so than the countless others she had indexed. 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. As a security measure, she remotely destroyed all the Keyships under her command, 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, with the Librarian perishing as the pulse struck Earth.

In the Covenant religion
The Librarian, has been known to the Covenant since fairly early on, with the epic poem known as the Kandonom Codex shedding light as to some of her activities. Known in the Covenant common language as Nedrallith, she occupies a key place in the 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. Since the Forerunner records available to the Covenant were largely corrupted and incomplete, her role in saving life from the rings also mangled. Her indexing efforts are rationalized as a way of preserving species who were not yet ready to come along the Path with as the Forerunners ascended, and so had to be safeguarded from the rings' Divine Wind. 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 must have been inherently worthy of the Journey. This is why the Covenant generally did not take pride in wars of extermination, and sought to downplay them in their history, and was one reason why the Human-Covenant War was so disruptive. The Librarian is also sometimes credited with blessing the rings's "divine wind" with the ability to initiate the Great Journey for the faithful, whereas the dreaded Flood would be mercilessly purged.