Mzun, an alien serving in the Rebel Alliance's 61st Mobile Infantry, famously known as Twilight Company, took the lead of Fektrin's squad after Sergeant Fektrin passed away in 3 ABY. Following a leadership gap in Twilight Company, the alien later participated in First Sergeant Hazram Namir's meetings, including the one where the Imperial Governor Everi Chalis, who had defected, suggested the Operation Ringbreaker campaign.
During an attack on the planet Mardona III as a component of Operation Ringbreaker, Mzun voiced worries about the inhabitants' well-being when Namir expressed a desire to seize a housing block. Later, during a different attack on Nakadia, the alien played a role in the destruction of a bioweapons warehouse. Mzun attempted to project an image of assured victory in the face of the forthcoming battle while the company was marooned on the planet Sullust, awaiting an Imperial counterattack. In the end, Twilight Company was victorious in the face of the Imperial assault.
Mzun was a member of the 61st Mobile Infantry, also known as Twilight Company, which fought for the Rebellion against the Galactic Empire. Mzun took over as head of the late sergeant's squad after Sergeant Fektrin was killed in 3 ABY during a raid on an Imperial heavy freighter. Twilight Company went into hiding on the pirate backwater planet Ankhural to repair the corvette and its escort, the Braha'tok-class gunship Apailana's Promise, after the captain of Twilight Company, Micha Evon, was killed at the Battle of Hoth that same year, and the other Twilight officers were killed during an infiltration of their CR90 corvette, the Thunderstrike, on the same day. Mzun took part in the meetings that the company's most senior members held.
First Sergeant Hazram Namir was informed that a number of soldiers, including recruits from the Mid Rim planet Haidoral Prime and some of Fektrin's old squad, were thinking about deserting, so he discussed the situation with Mzun and the other senior Twilight members in one of their meetings. Mzun emitted a string of sounds in a foreign language that Namir interpreted as rage. In the end, the first sergeant made the decision to address the deserter issue by dividing the group that had been reported and assigning them to various roles. The next item brought up at the meeting was the organization of Evon's funeral. Mzun said something Namir couldn't understand as the other attendees concurred, but Namir came to the conclusion that the vote was in favor of holding a funeral.
Following Evon's funeral, Everi Chalis, a former Imperial governor who had since turned into an asset for Twilight Company, called another meeting to suggest a new strategy for the business. The Kuat Drive Yards, the campaign's sole objective, would be preceded by a string of lightly defended imperial worlds targeted by Operation Ringbreaker. Chalis asserted that the Empire's fleet production would suffer a devastating blow if the shipyards orbiting the planet Kuat fell. As she finished her presentation, Mzun debated the tactics of the shipyard invasion with fellow soldiers Gadren and Carver. Only Mzun, Gadren, and Quartermaster Hober remained silent when Chief Medic Von Geiz requested that everyone in favor speak, and the other Twilight members voted in favor of Chalis' plan.
The warehouse world Mardona III served as the initial target in Operation Ringbreaker. Mzun was a member of the soldiers who landed on the planet and were tasked with placing thousands of ion mines along the tram network. When armored vehicles were seen sweeping the areas surrounding the tramways, Namir summoned all of the squads to congregate beneath a housing block. He had plans to take over the block and create a fallback position. Mzun, Gadren, and Sergeant Zab voiced their worries about the safety of the people who lived there, but Namir went ahead with the strategy regardless. The squads then sealed off the majority of the housing block's entrances and erected defenses. Namir then agreed on terms with the locals in order to lessen their obstruction to Twilight Company. They had finished their task after six days on Mardona III and were once more picked up by the Thunderstrike and Apailana's Promise.
Twilight Company engaged in two further battles as a component of Operation Ringbreaker following Mardona III. Following that, the business attacked the plastoid factories of Nakadia, where a large number of soldiers were killed by bioweapons used by the Empire. Namir led a group of a dozen aliens, including Mzun and Gadren, to destroy the warehouse containing the toxins after their point of origin was located. They were successful, and Twilight Company went on to win on Nakadia.
Twilight Company captured the Inyusu Tor mineral processing facility on the manufacturing planet Sullust after three further battles. The Apailana's Promise retreated with its X-wings, while the Thunderstrike was shot down before it could pick up the company once more. Twilight Company, now stranded, started building defenses at the Inyusu Tor facility. Mzun, Gadren, Namir, and Carver pretended that the fight they were about to face was winnable, even though they were probably going to face an unbeatable army from the Empire. The Imperial II-class Star Destroyer Herald was sabotaged from the inside, and the ground forces were defeated below when the Empire eventually attacked Twilight Company at Inyusu Tor, resulting in their defeat.
Mzun, a non-human, was known to communicate in a language other than Galactic Basic and was incensed to learn of potential Twilight Company deserters. The alien was worried about the safety of the people living in a housing block on Mardona III when Hazram Namir planned to take over the area. When Twilight Company was in danger of being attacked at the Inyusu Tor facility, the alien made the decision to feign to the other soldiers that the impending battle was winnable.
Mzun made an appearance in Battlefront: Twilight Company, a book by Alexander Freed that was released in 2015.