Sicinius honed his skills as a researcher at the Resonatorium in the service of Lord Aulus mal Asina. When the facility was decommissioned after the fall of Ala Mhigo and the findings of its team transmitted to Garlemald, the accomplished Sicinius received orders to return to the imperial capital. He rebuffed his superiors' advances, however, and instead requested a transfer to the IVth Legion, which he knew to be in pursuit─and if the rumors were true, already in possession─of lost reliquaries and forbidden knowledge of ancient Allag. The IVth, for their part, having heard whispers of Sicinius's consummate aptitude as a magitek engineer, had extended an invitation for him to join their ranks, making the two a natural fit. Upon joining the legion, his talents were quickly recognized by Legatus Gabranth and his second-in-command and leader of the archaeological expedition, Menenius rem Lanatus. Profoundly moved by Gabranth's vision for a new nation, Sicinius swore an oath of loyalty, and was thus rewarded with his current position of senior engineer.
Sicinius reported to Gabranth that the machinery in the Clockwork City of Goug was highly reminiscent of Garleans' own technology, implying that legends of Garlemald's ancestral ties to Ivalice were true.
In recent days, he continues his research with yet greater zeal, in hopes of restoring ancient warmachina and other technology recovered from the Ridorana Lighthouse, which stands in the Valnard Sea in the southern reaches of Dalmasca. Sicinius began his experimentation with the so-called laborer-class models, and it is believed the project has progressed to a point where he is looking to deploy these new machines on the field of battle. Indeed, it is said that he has volunteered to depart for the front lines of the war against the Bozjan Resistance, hoping to collect data on the potency of his latest toys firsthand─a trait doubtless inherited from his esteemed former master.
Many of the Empire's weapons have been sent to Valnain, where they undergo enhancement under the supervision of Sicinius. Two notable fruits of this project are Vigilia and Gabriel, however to piloting these units demands a heightened state of mental sensitivity verging on telepathy, and only those soldiers who have been augmented with magitek can achieve the requisite synchronization. Sicinius resolved to test it in Bozja and he required a test subject. In the IVth Imperial Legion, testing is only permitted upon living men when their safety is absolutely assured, and be it friend or foe, all individuals are to be treated with compassion. Perverting his commander's noble intent for his own ends, Sicinius reasoned that he was saving Dabog's life—a dying prisoner—and proceeded with his testing in secret.
When the Bozjan Resistance was approaching the Dalriada in Zadnor, Lyon states that Sicinius had "scurried off to some far-flung hole" instead of working on preparing the Diablo Armament despite it being his project.
When the IVth Legion lost their battle in Bozja, Sicinius reported to Gabranth in Valnain that they had successfully retrieved weapons that Menenius excavated before his death.
Six months after the Bozja battle, Gabranth was attacked by Lyon rem Helsos in rage for being blamed for their loss, and seemingly killed. The IVth Legion was defeated, its territories freed, and its officers including Sicinius went into hiding. Three months after that, however, Lyon arrived in Valnain with a captive Sicinius. Once Lyon had handed over his captive, he vanished without a trace. The Dalmascan soldier who oversaw the matter assumed that Lyon was a mere bounty hunter, and failed to realize he was the man once feared as the Beast King. Sicinius himself was bound and unconscious at the time, and even when brought to trial, he seemed to be unaware that Lyon was the one who had captured him.