Jerome was born around 2511 and was of a genetic make-up that the Office of Naval Intelligence and Catherine Elizabeth Halsey were interested in. After being selected as a suitable candidate for the SPARTAN-II Program in 2517, he was abducted and sent to Reach, where he was specially trained to be a soldier. In 2525, he and the other candidates underwent a series of augmentations to improve their physical and mental abilities. Jerome was among the ones that survived and were not crippled or killed by the procedure.
During his training, he quickly proved himself to be considered one of the program's top candidates. Both Dr. Halsey and Chief Mendez identified him as one of four emerging leaders within the Spartan-II group, along with Kurt-051, Frederic-104, and John-117.
Jerome's leadership skills were correctly observed, as he later became the earliest known appointed leader of the Spartan-II's Red Team.
Battle of Arcadia
Jerome was the appointed leader of Red Team during the First Battle of Arcadia. He and his team were tasked with stopping the Covenant long enough to evacuate the civilians of Arcadia. Afterward, he and Red Team linked up with forces from the Spirit of Fire and assisted in a counter-attack on a Covenant outpost. Once the plan to infiltrate a large Covenant shield was passed down from Captain James Cutter, Jerome and Red Team remained with the crew to assist with the assignment. He prevented the destruction of several prototype Rhinos while they ensured that the shield was destroyed. After Sergeant John Forge's forces triumphed over a Scarab, the three searched for Covenant survivors in the jungles on a Warthog. Upon hearing that Professor Ellen Anders had been abducted by the Arbiter, they went to the Spirit of Fire which jumped into Slipspace, following the Covenant ship carrying Anders.
Jerome-092 fighting at the Battle of the Apex.
Later, upon arriving at a Forerunner Shield World, Jerome assisted the Spirit of Fire's crew in neutralizing Covenant and Flood forces. Once Jerome assisted in destroying a Proto-Gravemind he and Red Team became stranded on the planet. With the Spirit of Fire being dragged inside the megastructure, Red Team was assisted by the forces of Sergeant John Forge and successfully withdrew to the ship. Red Team then assisted the crew in scouring the Flood forces from the hull of the Spirit of Fire and successfully repaired the power core when it was damaged.
Once Anders was rescued, he was tasked with ensuring the Spirit of Fire's Shaw-Fujikawa Translight Engine arrived at the teleporter that would take it to The Apex's command centre. In the control center, Jerome, along with Alice-130 and Douglas-042, engaged a large force of Honor Guards while Forge engaged the Arbiter. Once the area was clear, Jerome volunteered to take the slightly-damaged drive in and ensure its destruction. Sergeant Forge, believing that Spartans would play a bigger part in the war than he ever could, took his place. Jerome (with the Spirit of Fire's crew) was then charged with opening the gate which allowed the Spirit of Fire to exit the Shield World.
It is assumed that Jerome, as with the rest of the crew, entered cryo-sleep after the Spirit of Fire escaped the destruction of the Shield World.