Despite his veteran status, Aquilanus chose to remain in the Fourth Company to serve alongside his mentor and long-time friend Egon Talorus. Since Aquilanus joined the Second Tactical Squad during the Burning of Nilanthius in 786.M41, Talorus nurtured the potential for greatness he saw within Aquilanus, and since the Battle of Vardor VIII has considered Aquilanus his unofficial second-in-command. When the squad was split down into combat squads, Talorus would typically lead one and Aquilanus would lead the other. Aquilanus would also take charge of the squad outside of combat when Talorus was off attending to other matters of importance.
Aquilanus was quiet, rarely speaking unless spoken to or if absolutely necessary. Unlike Sergeant Talorus who reveled in combat at all ranges, Aquilanus preferred ranged combat to melee combat, typically equipping his Boltgun with an M40 Targeter to help aid his accuracy at especially long ranges.
After Egon became a Primaris Marine in 999.M41 and left the Fourth Company to aid in the command of the newly formed Eleventh Company, Aquilanus took up command of the Second Tactical Squad, finally ascending to the rank of Veteran Sergeant.