Keystone

This article contains information about the Silver Timeline, and is not a part of the established Halo canon.

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A Keystone buried in the caverns on Madrigal.

A Keystone is a Forerunner artifact that holds Forerunner information.

Overview

At least one keystone was buried on the planet Madrigal with another keystone that went together with it on Eridanus II. The keystone could display a holographic Forerunner script which led to at least one Halo ring. Furthermore, the keystone has shown the ability to mass EMP and repower UNSC equipment. When touched, the Keystone is able to scan the person who touches it, and awakened locked memories in John-117. However, each time that John used the keystone it placed a strain on his heart and nervous system.

When the Madrigal keystone was activated and John was put into stasis by Cortana so that the AI could access it herself, the artifact immediately shut itself down, seemingly needing John to be conscious to work. Later, after removing his emotional regulator, John realized that his altered hormonal state might've been affecting his interactions with the keystone. Following the regulator's removal and the restoration of a normal hormonal state, John's unlocked memories became clearer to him and easier to understand. After using the more powerful Eridanus II keystone, the effect on John's memories was stronger with John regaining blocked memories even when he wasn't touching the keystone.

Doctor Catherine Halsey suggested that the Madrigal keystone had its own intelligence given the way that it seemed to either respond to John's needs or anticipate what the situation required when he activated it.

Each use by John of the keystones resulted in him becoming sicker and sicker to the point that Condor 325's computer read his status as critical. According to Makee, a number of lesser keystones had the same effect on her until she learned not to fight them and to surrender to the visions. When John used the keystone again, he experienced a dangerously accelerated heartrate with Makee, who was in a completely different room, experiencing the same thing. When John followed Makee's advice and didn't fight the visions that the keystone showed him, his condition stabilized and he was transported alongside Makee into a vision of a Halo ring. While this was happening, John and Makee had completely identical bioreadings.

After John and Makee's combined use of the keystone to see Halo, the nature of their connection shifted to the point that the keystones remained inactive unless they were touching them at the same time. When John approached one keystone, the other one in Makee's possession lit up in response.

History

Madrigal Keystone

In 2552, the Covenant launched an attack on Madrigal for the keystone, wiping out a nearby Insurrectionist outpost. The Spartans of Silver Team eliminated the attacking Sangheili and John-117 and Kai-125 entered the cave where the Covenant had been excavating for the artifact. Upon finding the keystone, John touched it and the artifact reacted to the touch of a Reclaimer, lighting up the entire cave and displaying symbols. It had a surprising effect on John, apparently unlocking some of his sealed memories of his childhood. The artifact's reaction to John was noticed by a surviving Sangheili who managed to escape and report it back to the Prophet of Mercy who had learned of the artifact's location from Makee.

Throughout his return trip to Reach, John remained fascinated by the artifact while Dr. Catherine Halsey became concerned about its effects on John and his memories. After John rebelled rather than execute Kwan Ha, the UNSC shot down his Condor with an electromagnetic pulse, knocking the artifact loose from its casing in the process. John touched it, causing the symbols to display once again and for John to experience more of his memories. In one of his memories, a young John drew a picture of the artifact for his mother. The artifact then let out a pulse that knocked out power to the UNSC base while restoring power to John's Condor, allowing John to escape from Reach with Kwan and the artifact.

John subsequently took the keystone to The Rubble to seek out Soren's help. Soren's touch failed to elicit a reaction from the keystone and he introduced John to Reth, a man who had been on one of the Covenant ships and had been tested as a Reclaimer. Like with Soren, the artifact also failed to respond to Reth. When Reth shoved the keystone into John's hand, it triggered a pulse that caused everyone but John great pain and for the symbols to display once again as well as causing John to see more of his childhood memories. John quickly returned the keystone to its box, ending the effects. Reth explained that the ring that it had displayed when activated was what the Covenant and a door to the end of life as they knew it. Reth confirmed that the ring was a weapon and after John admitted that he could feel the darkness, Reth urged John to destroy the keystone and then himself. However, John then decided to take the artifact back to the UNSC where it was studied by Halsey who described it as being nothing like she'd ever seen before.

At the same time, on High Charity, Makee and the three Covenant Hierarchs listened to the surviving Sangheili warrior's testimony about what he had seen. Alarmed that the Demon had gotten his hands on one of the keystones, Makee decided to pursue it herself. Makee attacked the UNSC Gladius with the help of a Lekgolo colony, but they failed to get any information from either the crew or the ship's database which was wiped during the attack as per the Cole Protocol.

Admiral Margaret Parangosky later told Miranda Keyes that results confirmed that the keystone was over 100,000 years old which Miranda was stunned by, calling it pre-human and possibly even pre-Covenant. Miranda noted that the keystone was organic, but with what appeared to be an inherent technology. Parangosky revealed what John had learned about it leading to a weapon somewhere and asked Miranda to lead a team analyzing the artifact to determine what it was, what it did, if it was in fact a part of some kind of a weapon or anything that could give humanity an edge over the Covenant. Parangosky sought to create parallel teams studying in the artifact in order to find a way to be less reliant on Halsey in the future.

Under monitoring by Halsey and Adun Saly, John activated the keystone once again, triggering more of his childhood memories featuring a young John drawing and exploring a glowing cavern. As John reached for something in the memory, Halsey had Cortana put John into stasis so as to have Cortana access the artifact herself. However, as soon as Cortana shut John down, the keystone deactivated itself and Cortana got no readings from it at all. Halsey had Cortana release John who called this experience with the artifact "different" than the previous times. With Cortana's help, John later attempted to locate the planet from his memories using the FLEETCOM Central Database.

After removing his emotional regulator and having an epiphany after seeing a dog in the park, John returned to the artifact and had Cortana, with Halsey's consent, override the lock on the room's door. Despite Cortana's warnings that touching the keystone put a strain on his heart and nervous system each time, John activated it once again and unlocked more of his childhood memories which revealed that he drew both the Madrigal keystone and another larger one, showing his mother that the two artifacts went together and that John's father had eventually forced him to bury something against his will. With the added information from his newly-unlocked memories, John identified the planet that the second keystone was on as Eridanus II. John subsequently explained to Halsey that John had realized that his altered hormonal state from the regulator had been messing with his interactions with the keystone.

While John and Halsey were away searching for the Eridanus II keystone, Miranda tested the Madrigal keystone on Silver Team, but it failed to react to any of the other Spartans. After discovering that the Spartans knew some of the Sangheili language in the process, Miranda enlisted Kai-125's help to translate Makee's message to her ship following the attack on the Gladius. The two translated the word "keystone" which they realized likely meant the artifact and accessed the recording of John first activating the keystone. Miranda and Kai realized that the ring displayed on the activated keystone was the Sacred Ring or Halo that Makee was talking about. Kai agreed to Miranda's request to keep their discovery hidden until Miranda could figure out what it all meant.

Makee and a team of Sangheili examined the cavern that had held the keystone with Luminaries in the hopes of finding a trail to lead them to the second keystone. After the Eridanus II keystone let out an energy pulse, the Luminaries picked it up. Touching the spot on the wall where the keystone had resided, Makee saw where the second keystone was.

Makee later claimed that she could use the Madrigal keystone to find the Eridanus II artifact which had been stolen by the Covenant. Miranda had suspected that the two keystones were communicating and suggested testing Makee. However, John was unwilling to let Makee go anywhere near the keystone and instead suggested trying to use it to find the other keystone himself since John and Makee were the same. However, Miranda wasn't comfortable testing it on John who was getting sick from using the keystones and she worried that Makee wanted them to kill him off the Covenant's most powerful enemy. Regardless, John insisted upon trying anyways.

Monitored by Miranda and, secretly, Halsey and Adun Saly, John activated the keystone once again which also affected Makee in a different room, causing Makee to collapse and both of them to have an accelerated heartrate and John to start to go into circulatory failure as he experienced a number of his childhood memories. Wanting to see the outcome, Halsey refused to let Cortana shut John down to end the danger to him. Finally, John stabilized as he was transported into a vision alongside Makee into a vision where they were standing on a Halo ring.

Six months later, the Madriga