Olivier, formally designated Olivier of Obsidian (オリヴィエ, Orivie), holds the rank of Chasseur within the Catholic Church. His physique is slim and of average height, complemented by pale skin. He displays a thin, angular face with narrow upturned eyes, long eyelashes, and sharply defined eyebrows. Long dark hair flows to his hips, usually tied in a loose ponytail that obscures his left eye. He adorns the standard Chasseur uniform: black pants, a cassock, a white harness, a purple ribbon-like belt, and dark leather boots. A dark purple obsidian rosary hangs around his neck.

Personally, Olivier is high-strung and quick to agitation, particularly provoked by Roland Fortis’s breaches of decorum. He prioritizes efficiency and protocol, showing impatience toward incompetence or defiance. Though outwardly polite and restrained with acquaintances, he judges unreasonable actions harshly. Narcissistic pride marks his demeanor, alongside noted popularity. Despite minimal emotional display, he exhibits sharp intuition and strategic intelligence, often calculating others' feelings—especially Roland’s—while concealing deep loyalty that drives him to trust, defend, and support those he values.

His narrative emerges in the Hunters of the Dark Arc when he interrogates Roland after Vanitas and Noé flee the Chasseurs’ compound, questioning him about seismic disturbances from Moreau’s malnomen experiments. Roland confesses his transformed views on human-vampire bonds, leading Olivier to urge discretion. Later, during the Return of the Beast Arc, Olivier tracks Roland to Mira’s laboratory library. Upon uncovering Roland’s shifted perspective on vampires, Olivier cautions him about potential fallout for his family if Chasseur superiors discover his heresy. Roland retaliates with threats against the Chasseurs and Olivier himself, inciting Olivier’s frustration.

In combat, Olivier wields Hauteclaire—a unique, non-rotating chainsaw-like blade. His fighting style is brutally destructive, often damaging or shattering the weapon.

Relationships define him significantly. His decade-long bond with Roland Fortis anchors his story: Olivier once secured Roland’s promotion to Paladin (Jasper) hoping to instill responsibility, yet remains exasperated by Roland’s irreverence. After serving as Olivier’s vice-captain, Roland now leads his own unit. Olivier actively suppresses Roland’s pro-vampire realizations, fearing Church retribution, though Roland ignores these warnings. Their mutual devotion is profound—Roland nearly dies shielding Olivier, who keeps vigil at his bedside, contemplating abandoning the Church if Roland perishes.

Olivier regards Astolfo Granatum as a troublesome younger sibling, receiving far greater respect from Astolfo than Roland does. He openly despises Gano, refusing greetings and recognizing his troublemaking nature. When Gano mocks the tragedy afflicting Astolfo’s family, Olivier seizes his collar, nearly escalating to violence to silence him. Mutual hatred fuels their dynamic, intensified by Olivier’s close friendship with Roland, whom Gano loathes.