Primordial

"We meet again, young one. I am the last of those who gave you breath and shape and form, millions of years ago. I am the last of those your kind rose up against and ruthlessly destroyed. I am the last Precursor. And our answer is at hand."

- The Timeless One speaking to the Didact.

The Timeless One also called the Captive by Forerunners, and the Primordial by ancient human warriors, was an individual of great power detained on Charum Hakkor. Unbeknownst to most of the galaxy, this individual was the last known living Precursor.

History
The creature was discovered by prehistoric humans on a "half dead" planet. Yprin Yprikushma then transported it to a vast arena on Charum Hakkor some time after humanity colonized the planet, where it was then contained within a capsule of Precursor origin. Despite the advanced nature of Precursor technology, the humans managed to find a way to communicate with the captive for brief periods of time. They came to regard the creature within the cell as an oracle of sorts, asking it questions in the hopes of gaining greater understanding. Most of the time, the prisoner's answers were confused or unintelligible. It was theorized that the captive may have been preserved as an ultimate weapon of last resort, to be unleashed in case of an imminent defeat of the humans and the San 'Shyuum.

When the Flood were first encountered in the Milky Way, several humans questioned the prisoner as to the nature and origin of the "disease". When the prisoner gave them an answer, the humans present were so deeply horrified that many of them committed suicide. Shortly afterward, the captive's cage was sealed with a time bolt as a further precautionary measure. Following the end of the Human-Forerunner wars, the Didact and a group of Prometheans gained access to the prisoner. It told the Didact that it was the last Precursor, and that the Forerunners had rebelled against the Precursors. The Didact revealed this information to no one with the exception of his wife, the Librarian.

When the Mendicant Bias tested a Halo installation in the Charum Hakkor system, the Halo's energies destroyed every Precursor structure on the planet, freeing the prisoner. The creature was then taken to Mendicant Bias' Halo for study; both the Halo and Mendicant Bias disappeared soon after, not to return for 43 years. Later during the Forerunner-Flood war, he used the Palace of Pain as a stronghold on Mendicant Bias's Halo.

During this time period, Mendicant Bias conversed with the Primordial, who in turn explained the purpose of the Flood, the nature of the Mantle, and the eons-long plan of the Precursors. Understanding the fact that the being in question was in fact a Gravemind, a physical embodiment of the Flood's collective consciousness, Mendicant Bias was eventually persuaded by the Primordial/Gravemind's arguments, and deliberately succumbed to Rampancy. The AI then defected to the Flood, and referred to the Gravemind as its master, demonstrating its denial of the Forerunners.

Later, the Didact imprisoned the Timeless One, and alongside the wounded Chakas, interrogated the entity. During the course of their conversation, they came to realize that the Timeless One is not what they initially thought it was. Even as it was being broken down by the reversed stasis chamber, the Primordial claims that the Flood and the Precursors are synonymous. The Primordial provides further clarification on the subject of the Mantle, the purpose of the Flood, and the role of the Humans in its ancient plan: the Forerunners were never meant to inherit the Mantle, and that Humanity would succeed them in order to be tested for inheriting the Mantle through the challenge present in the Flood.

It also implies that there is no true cure for the Flood, but that it could choose whether or not a victim was infected. Once this conversation is complete, the Didact fully activates the reverse stasis chamber, forcing an artificial decay process equivalent to a billion years to transpire over the course of several seconds, killing the Timeless One, and breaking its body down to a state of complete physical entropy.

List of appearances

 * The Forerunner Saga
 * Halo: Cryptum
 * Halo: Primordium