859 Static Carillon is a Forerunner Ancilla and Monitor of the Composer's Forge. In 2558, he met the Ur-Didact while investigating the lack of response from 049 Abject Testament on Gamma Halo. Knowing that the Composer's Forge would supply him with additional Composers with which to digitize Humanity, the Ur-Didact ordered Static Carillon to take him there.
On July 25, 2557, Static discovered that the service portal to Installation 03 was open and tried to contact the ring's Monitor, 049 Abject Testament for an explanation, but received none, so he decided to investigate himself. Upon arriving on the Halo, Static was puzzled by the absence of the Composer and the mysterious presence of Promethean Crawlers, before running into Ur-Didact. After Static affirmed his identity and function, the Didact asked to be shown to the Composer's Forge. The Didact and Static subsequently made a pact; in exchange for not disturbing his facility, Static would teleport Installation 03 above the planet where the Forge was situated.
The day after, Static informed the Didact of the arrival of humans, John-117 and Blue Team, who had found the Composer's Abyss. This led to the Didact manufacturing more Prometheans to attack the Spartans, which upset Static, who protested using tortured human souls to create Prometheans. The Didact grabbed the Monitor, demanding to know why he hadn't upheld his end of the agreement, at which Static teleports the Halo directly over the planet. As the Didact departed with one of the six Composers from the Forge, subsequently, Static decided to aid John-117 and his comrades, revealing the Didact was planning on firing the Halo near Earth to wipe out humanity, and fought against the Prometheans to buy the Spartans time to return to the ring. After some time, Static followed suit and found the Spartans being overpowered by the Didact. The Monitor blasted the Didact in the back, knocking the Activation Index out of his hand, and teleported the Forerunner to the Control Room. As the Spartans recovered, Static advised them to prevent the Didact from attuning his armor to their weapons, which gave John-117 the idea to use the Halo to kill the Didact. However, the Monitor reminded that doing so would wipe out all life within a twenty-five thousand light year radius and suggested a plan to limit the destruction. He teleported the Master Chief into the Control Room to reunite the Index with the core, before manually deactivating safety protocols so Static could eject the section of the ring they're on onto the planet. Doing so creating gravimetric anomalies that nearly destabilized the ring had not Static took a moment to attend to them before teleporting himself and John-117 onto Blue Team's Longsword. Static then thanked the Chief for his efforts, stating that he found new meaning through him, before departing to take the Halo away for repairs.