Walker first appeared on Pluto with a mission from SICON Military Intelligence to retrieve a baby Plasma Bug for scientific research. Since the mission was designated an Intel offensive, Lieutenant Walker held command. He specifically requested Roughnecks Alpha Team to escort him during the mission and aid in the capture of the target bug. At first, Walker's egotistical attitude irritated the squad, including its leader Lieutenant Razak. Walker demonstrated an apparent lack of concern for the lives of human personnel as long his priorities were met. The squad had only 24 hours to accomplish their mission, including salvaging vehicles from an abandon outpost, locating and securing a baby Plasma Bug and rendezvousing with a retrieval boat all in enemy-held territory. Walker's objective was achieve, albeit increasing danger to Razak's squad. During the rendezvous with the retrieval ship, they were met by Fleet Lieutenant Zander Barcalow. Walker showed as little respect to Fleet Officers as he showed towards Mobile Infantry Officers.
During the flight across the planet, Lieutenant Barcalow informed both Lieutenants Walker and Razak about the ongoing ground battle that was occurring the same time as Walker's Intel mission. According to the report, ground squads were losing the battle to massing bug forces. While on board, the previously sedated Plasma Bug had awoken and grew increasingly uncontrollable. Lieutenant Razak improvised a bombing run with Barcalow, against Walker's protests. The bomb-run called for the Plasma Bug being dropped over the battlefield. Because of the Plasma Bug's naturally unstable biochemical nature, the impact-drop caused a chain reaction, resulting in multiple explosions that engulfed other Plasma Bugs on the ground as well as the mass Warrior Bugs on the field. The results of the Plasma Bug drop were a successful direct hit over the bug forces, saving countless lives. Selflessly, Razak offered Walker the opportunity to report the bug-drop as his idea to SICON Headquarters, promising Walker the likelihood of winning a medal. It was learned that Walker did in fact claim credit for the bug-drop and thus was awarded a medal for the deed.
At a certain point, Walker was willing to ensure that Razak's military career would end during General Miriam Redwing's supposed disappearance being unaware of Redwing and Razak's sting operation against a mole within the SICON ranks.
During the Homefront campaign, Walker and Razak along with their squads managed to put aside their differences and befriended each other. Walker is not seen after Razak's death except for taking command of his squad fighting elsewhere during the conflict.