Emotional regulator

"For his own safety and for ours, John doesn't feel as we do. Hormonal pellets have suppressed his emotions."

- Doctor Catherine Halsey to HIGHCOM

The emotional regulator was a hormonal pellet embedded in the lower spine of Spartan in order to suppress their emotions.

History
At some point, the pellets were embedded in the lower spine of the Spartans in order to suppress their emotions. The Spartans were told that the pellet enhanced their battle focus.

In 2552, after John-117 went rogue, Dr. Catherine Halsey told UNSC HIGHCOM about the pellets and their effects while trying to get them to approve the implementation of "the Cortana system."

On the Rubble, Soren told John that the pellet in his back that enhanced battle focus also muted everything else and made him "as numb to life as you are to the taste of this food." Soren described losing the pellet and its effects as being like opening your eyes for the first time after living in the dark.

While trying to find the planet from his childhood memories, John came across Mamore where he recalled losing Nora-098, something that he felt nothing towards. Cortana explained that the pellet in John's spine prevented adverse emotional responses and protected mission readiness, but John was feeling as well as seeing the memories that were being unlocked by the Forerunner keystone.

As a result, John decided to remove his emotional regulator. Although Cortana warned Halsey as the removal was against Section Three, Regulations on Spartan Behavior, Halsey ordered the AI to help John rather than put him into stasis again. Halsey promised to take care of the pellet herself, but it was better for John to see Cortana as an accomplice rather than a spy. Cortana directed John on where and how to cut into his lower back and he successfully removed the regulator. Unseen by either John or Cortana, Kai-125 secretly witnessed John's actions. After cleaning the pellet, John stored it in his locker.

Following the regulator's removal, John accessed the keystone again and unlocked more memories that revealed the existence of a second keystone on Eridanus II. John explained to Halsey that he'd realized that the altered hormonal state that the regulator was putting him in might've been affecting John's interactions with the artifact. At the same time, on Reach, Kai also removed her emotional regulator.

List of appearances

 * Halo: The Television Series
 * Unbound
 * Emergence
 * Homecoming