In his early years, Jai was an orphan until he was conscripted into the SPARTAN-II Program in 2517. When he was told that he had been conscripted, he attempted to leave the compound, but one of the trainers was able to take hold of him. Over the next five months, he constantly attempted escape with another SPARTAN-II, Adriana-111. The trainers, after suffering broken ankles, lost eyes, fingers, and toes, chose to shoot them with darts from the troop bays of Pelicans, after they tried unsuccessfully to capture them using stun devices on the ground.
Formation of Gray Team
Jai was eventually sent to meet with Dr. Catherine Halsey. Upon telling her that he wanted to go home, she showed him a dart that induced neural paralysis, meaning that he would forget everything about the SPARTAN-II program. She informed him that when he would wake up, he would find himself in a city with no memories of the last five months. However, he was also told that it reacted badly to children, erasing their entire memories. Continuing her speech, she went deeper into his head, asking him how he would feel if he forgot Adriana, whom he seemed to like a lot, and telling him that the orphanage he used to live in hadn't noticed he had been missing: this may be because the Spartans were replaced with flash clones. The thought of losing his memory was enough to discourage any more escapes.
The night after the discussion with Dr. Halsey, Jai made one final escape attempt, but after catching up with Adriana, he decided that it would be best to return to the base. The next day, Chief Petty Officer Franklin Mendez introduced Jai and Adriana to Mike-120, who admitted to stealing a Pelican by himself and blowing it up when the UNSC came after him. These three later became the Gray Team, a renegade squad that preferred to be far from the chain of command, but deeply enjoyed fighting the Rebels and the Covenant behind their own lines. After surviving the augmentation process, Jai became the leader of Gray Team. His position of leadership was a somewhat tenuous one. Both Adriana and Mike did not truly acknowledge his command of the squad, somewhat to Jai's dismay.
During the Human-Covenant war, Jai and the rest of Gray Team operated behind enemy lines, wreaking havoc on both the Covenant and the remaining rebels. They flew through Covenant and Insurrectionist-held space, looking for targets of opportunity, in their ship and base, the Petya.
Battle of the Rubble
At The Rubble, Gray Team battled the Covenant and rebels to keep UNSC navigation information out of Covenant hands. Jai disapproved of Adriana's favoritism of Ignatio Delgado, who he believed was an Insurrectionist and did not trust. Shortly before the Battle of the Rubble, Jai was assigned to rescue Ignatio Delgado. He ended up finding Delgado, barely alive, and Diego Esquival, who had been killed. Delgado told Gray Team that Peter Bonifacio was stealing the navigation data so he could sell it to the Kig-Yar, and decided to stop Bonifacio before aiding the AI Juliana (he took note of her "quirky" personality and believed she was rampant).
Gray Team then formulated a plan to stop Bonifacio and the Covenant. Jai had the idea of freeing the captured crew of the UNSC Midsummer Night in order to have a substantial fighting force. He personally freed the crew, including Lieutenant Jacob Keyes, and briefed them on the situation. Alongside ODSTs led by Faison, He stormed the Kig-Yar ship Infinite Spoils. When Thel 'Vadamee, Zhar, and some Unggoy boarded the Infinite Spoils in an attempt to retake the ship, Jai, who was informed by Delgado that Faison was lying injured in the ship, attempted to find the ODST. He ran into Thel and Zhar, and managed to match Thel in combat. He realized that they had already killed Faison, and returned to Keyes afterward.
After returning to the relative safety of Habitat Tiago, Jai had an idea: Keyes had all of his forces suit up and prepare for vacuum exposure, while only a few Covenant were prepared. With the help of the AI Juliana, they could blow the atmosphere out of the habitat, killing most Covenant forces. Jai risked his life to place Juliana into the atmosphere control console, gaining the trust of Delgado and the rest of the rebels. Juliana then blew out the air from Habitat Tiago, ending the Battle of the Rubble.
Battle of Metisette
The remaining UNSC forces soon discovered the hundreds of thousands of Unggoy living nearby on Metisette, preparing to mobilize. Jai was in favor of abandoning the Rubble (because, after all, none of the endangered residents were loyal to the UNSC but to the enemy), but Keyes was able to convince him to fight the Covenant. He led a group of ODSTs on Metisette, including Mutuku, Jones, and Adams. They were tasked with placing a Shiva-class Nuclear Missile in the Redoubt, which they accomplished quickly. Shortly after the Covenant anti-aircraft guns were silenced, they were evacuated from Metisette, and the nuke went off, damaging (but not totally destroying) the Redoubt.
After the Battle of Metisette, Jai and the rest of Gray Team reported to Falaknuma for debriefing. They planned to ask for (or forcibly take) a Prowler, and continue fighting the Covenant from behind their own lines
As of 2552, Jai and the rest of Gray Team were still alive and still fighting the Covenant, too far behind enemy lines to be recalled. However, Frederic-104 mentioned Gray Team to be missing since 2551.
- Halo: The Cole Protocol, page 69
- Halo: The Cole Protocol, page 76
- Halo: The Cole Protocol, page 238
- Halo: The Cole Protocol, page 250
- Halo: The Cole Protocol, page 275
- Halo: The Cole Protocol, page 279
- Halo: The Cole Protocol, page 290
- Halo: The Cole Protocol, page 317
- Halo: The Cole Protocol, page 353
- Halo: Ghosts of Onyx, page 221