Arnus was a Senator of the male Human species. He held his position in the Galactic Senate of the Republic throughout the duration of the Cold War.
The year 3643 BBY saw Senator Arnus initiate a holographic communication with General Elin Garza. He was seeking clarification on the swirling rumors concerning alleged desertions from SpecForce. Despite Garza's reassurances that these rumors were unfounded, the senator remained unconvinced. The general, however, abruptly ended the call, citing the need to attend to visitors in her office, leaving the senator unsatisfied.
Subsequently, Arnus convened an informal inquiry before a Senate committee. This committee, comprised of himself, Senators Voralla, and Zorin Krasul, was tasked with investigating the defection of the previous commander of Havoc Squad. The new CO of Havoc Squad was summoned to this inquiry. The CO truthfully acknowledged that the remaining members of Havoc Squad had defected to the Sith Empire. Arnus then inquired whether Harron Tavus and his fellow defectors had exhibited any indications of instability or discontent prior to their departure. Upon learning that their signs were subtle, Arnus questioned if the events that transpired on Ando Prime were linked to Havoc's defection. Voralla interjected, emphasizing the classified nature of the Ando Prime operation, and instructed the CO to disregard the question. Following this exchange, the committee dismissed the CO.
Around 3641 BBY, Arnus and his fellow senators called Havoc Squad back to Coruscant to participate in a hearing regarding the squad's recent actions. Upon the CO's arrival at the Senate, Grom Zian, the senator who initiated the hearing, began to accuse Havoc Squad of abusing their authority. He presented a series of accusations against the squad, including allegations of murdering Tavus and covering up the crime, provoking the Empire by destroying the Gauntlet without the Senate's consent, and demonstrating a general lack of contribution to the war effort. When the CO was given the opportunity to respond, the trooper presented evidence obtained by the SIS, which revealed Zian's status as a paid agent of the Empire. Zian's goal was to have Havoc suspended, thus enabling General Arkos Rakton to shift the balance of the war. The Chagrian senator attempted to dismiss the evidence as "wild accusations" and "paranoid delusions," but Arnus decided to examine the evidence. After the committee had thoroughly reviewed the evidence and confirmed its validity, Arnus instructed the Senate Guard to arrest Zian for high treason. Voralla then apologized to the CO for having doubted them and permitted the trooper to return to the front lines.
Arnus appears as a non-player character in Star Wars: The Old Republic, the massively multiplayer online role-playing game created by BioWare and launched in 2011. Fred Tatasciore provides his voice.