Malarus, a female human, held the rank of commander within the First Order circa 34 ABY. Following Agent Terex's unauthorized rogue mission aimed at eliminating the Resistance, she placed him under arrest. Terex was an agent of the First Order Security Bureau.
To secure sustenance during her youth, Malarus engaged in hunting, honing her skills by dedicating time to comprehending her targets. After Agent Terex of the First Order Security Bureau disregarded Captain Phasma's warnings and embarked on a rogue mission to annihilate the Resistance, the First Order dispatched Commander Malarus to discipline him. Malarus arrived at the desert planet where Terex was pursuing Poe Dameron with a Maxima-A class heavy cruiser accompanied by numerous TIE/fo space superiority fighters. Malarus' space forces eradicated the Ranc Gang's fleet of "Uglies" and obliterated Terex's flagship, the Carrion Spike.

Subsequently, Malarus spearheaded an Atmospheric Assault Lander, along with a detachment of stormtroopers and TIE fighters, to the planet's surface. She greeted Dameron and his droid BB-8 as they emerged from the cave alongside a disabled C-3PO and a crestfallen Terex. Following a brief exchange, Dameron cautioned Malarus that his Black Squadron was documenting their encounter in case she ordered an attack. Malarus commended Dameron for his political acumen before instructing him to surrender Terex. Dameron complied, but first informed Terex of his defeat before handing him over to Malarus.
Malarus, Terex, and her stormtroopers then boarded the bulk freighter Romary. Onboard, she interrogated Captain Perrili regarding her ties to the Resistance. Despite Perrili's insistence that her business dealings were purely transactional, Malarus commanded her execution and ordered the Romary to be rigged for detonation as their tanker commenced siphoning fuel from the Romary. Malarus then piloted the Enshado to a hyperspace ring, where she and the Enshado were intercepted by Dameron. Dameron demanded they depart without the Romary's fuel or face the destruction of the Romary. Malarus instructed her forces to delay Dameron's forces while the Enshado proceeded towards the hyperspace ring. Regrettably, Dameron's forces destroyed the ring. Malarus, mindful of their orders to avoid direct confrontation with the Resistance, directed the tanker's crew to abandon ship. Malarus then ensured the tanker was set to self-destruct. However, only the Romary was destroyed, and Dameron's forces seized the tanker.

Malarus then engaged in conversation with Terrex regarding Dameron. Subsequently, she and Terex journeyed to Abednedo with the intent of capturing Oddy Muva. Following Muva's capture, she instructed his wife, Sowa Chuan, to relay news of her husband's capture to Dameron. Aboard a transport, Malarus directed Terex to interrogate Muva for intelligence pertaining to the Resistance. She then received notification of approaching X-wings and the capture of Jessika Pava, Karé Kun, and their team at Spalex by another officer. Malarus then arranged for Dameron and Wexley to be brought aboard the Enshado. She subsequently piloted the Enshado to Spalex to apprehend the remaining members of Black Squadron. She then commanded Terex to eliminate Muva, deeming him a liability. However, Terex freed Muva, who then aided Dameron and Wexley in their escape. Malarus and Terex then boarded a Xi-class light shuttle bound for Spalex to eliminate the remaining members of Black Squadron. They were intercepted by Dameron and Wexley in their respective X-wings. Malarus then witnessed Muva execute a suicide attack on the Enshado before initiating her escape into hyperspace.

Malarus then traveled to Cato Neimoidia utilizing Dameron's own X-wing. Upon arrival, she disabled Dameron's astromech droid, BB-8, and engaged Dameron, piloting a fighter borrowed from Baron Paw Maccon, in head-to-head aerial combat. Throughout their dogfight, Malarus displayed no compunction about causing civilian casualties. She gained the advantage in the engagement, but as she prepared to deliver the final blow, BB-8 reactivated and assumed control of the fighter. Following BB-8's retrieval by Dameron in a mid-air ship transfer, Malarus crashed. She was then confronted by an official from House Reya, who placed her under arrest and informed her that she would face trial.

Malarus was a tall human woman with blonde hair and an amber right eye. Her left eye was artificially black as a result of a naturally occurring narcotic, which also enhanced her body-mass growth and intelligence, and slowed her aging. She kept her hair tied into a tight bun. Malarus expressed admiration for Resistance pilot Poe Dameron's political acumen.
Malarus made her debut appearance in the thirteenth issue of the 2016 Star Wars: Poe Dameron comic-book series. Charles Soule wrote the issue, Phil Noto provided the illustrations, and Marvel Comics released it on April 19, 2017. Soule instructed Noto to base Malarus's character design on Brigitte Nielsen's character from the film Rocky IV during Malarus's creation.