Since joining the Harbian Eclipse Agency, Monte has proven to be a talented and useful asset to the Corporatocracy. In the 2020s, Monte was dispatched to deal with the mysterious Enigma Brink region within the Zocuric Ocean -- only to discover that it was caused by a rogue Soviette cell, of which he led to its destruction. Another major mission for the HEA occurred in 2033, when Monte was tracking down the resurfaced Soviette cell that caused his father's death. He and his retired mentor, Ted Weston, endured Operation Housecleaning and eventually terminated all leading members of the Soviette cell. In 2046, Monte Montero was dispatched to the small Isteroxean nation of Cruale, to aid in the destabilization of its government.
On 2054, Monte Montero was tasked with eliminating a group of Karnali scientists who had supposedly been developing a bioweapon in a remote facility within the nation of the Karnal Isles. Upon enacting the HEA's operation, he discovered that the scientists were only using a custom gas that gave flora cancer, so that they could study it in hopes of curing cancer in humans -- the gas was toxic to humans, which is what the informant had failed to mention. This event, later known as the Undarska Research Team Massacre, scarred Monte and caused him to resign from the Harbian Eclipse Agency, as he deeply regretted his action in the botched operation. Shortly after his own resignation, Monte vanished without a trace. For over a decade, he remained MIA. In 2071, however, Monte Montero made himself known again. Between the time of his unknown whereabouts, Monte founded the self-proclaimed vigilante group the Sons of Ulciscor.