Nine-Four-El, a droid, provided his services to Beilert Valance, the cyborg bounty hunter, during the age of the Imperial Era. Valance was assisted by the droid in the acquisition of bounties, and Nine-Four-El also kept an eye on Valance's progress as he completed them. The cyborg was accompanied by Nine-Four-El in 3 ABY while searching for his former mentor, Nakano Lash, who was a Nautolan bounty hunter.
Sometime after the mission that the cyborg bounty hunter Beilert Valance received from his old friend Han Solo during the Imperial Era, Nine-Four-El, a droid, became his companion. In 3 ABY, Valance accepted a bounty that involved capturing members of a clan of Devaronians located in Black Spire Outpost on Batuu, a planet in the Outer Rim. Nine-Four-El cautioned him about a potential ambush by the clan. When Valance found himself pinned down in the outpost and the droid's warning proved accurate, the cyborg sarcastically noted that the droid had failed to mention he was leading him into an ambush. Nine-Four-El monitored his master's progress from aboard the Broken Wing, the cyborg's cruiser, throughout the mission.

As Valance returned fire on the Devaronians, Nine-Four-El reminded him that the bounty stipulated that the targets were to be taken alive. Valance retorted that the clan was not "cooperating." The droid reiterated the bounty's terms but was cut off and silenced when his master threatened to scrap him, adding that he was a reliable source of credits. With only one Devaronian remaining, Valance, having been disarmed, decided to use his palm blaster and pursued the Devaronian. Nine-Four-El then pointed out that the cyborg had not tested the repairs to the weapon and again tried to state the bounty's terms, only to be interrupted once more by Valance, who declared that the target would still be breathing at the end of the chase.
When the Devaronian commandeered a landspeeder, Nine-Four-El announced that the target had escaped. Valance responded that he would turn around and seek vengeance for his fallen clanmates. After Valance ripped a pipe off of a moisture vaporator because his palm blaster failed to activate, the droid inquired whether the cyborg's plan was to use the clan as bait. His master replied that the strategy was to use himself as bait, before striking the Devaronian off the speeder with the pipe and rendering him unconscious. The droid revealed that the reward for capturing the lone surviving Devaronian would cover the fuel and docking fees for the Broken Wing. Valance instructed the droid to find bounties that did not "waste his time." After examining several holopucks, Nine-Four-El complied and informed Valance about a peculiar bounty.

Upon learning of the resurgence of his former mentor, Nakano Lash, Valance, accompanied by Nine-Four-El, journeyed to the Safe House on the Outer Rim planet Eriadu in search of clues regarding Lash's last known whereabouts. At the Safe House, Nine-Four-El, standing amidst numerous corpses strewn across the floor, informed Valance that Lash's trail had grown cold and was instructed to continue searching. The droid identified the body of Jhorstek, an Abednedo black market supplier and an old contact of Valance's. He noticed the cyborg drinking and asked if he was sure that the supplier was connected to Lash.
After further investigation, Nine-Four-El reported to Valance that the building's cameras had been destroyed by blaster fire. When Valance broke through a wall and extracted a control panel, the droid reminded him of property regulations, before his master commanded him to activate silent mode via voice command while Valance reviewed security footage to identify Jhorstek's killer. After the bounty hunter Boba Fett was identified as the killer, Nine-Four-El and Valance traveled to Galmerah, the planet used as a graveyard, where Lash had last been seen.
Upon reaching Galmerah, the droid and Valance moved across the terrain until they arrived at the grave of Lash's parents. Nine-Four-El was then instructed to deactivate silent mode and translate the pheromones emanating from the grave, which he identified as the Nautolan language Nautila. When Valance touched the pheromones, the droid detected a change in their composition and identified map coordinates within them. They were then immediately confronted by Bossk, the Trandoshan bounty hunter, who was also seeking to claim Lash's bounty. After a brief exchange between Valance and Bossk, a fight broke out between them.
Nine-Four-El possessed silver plating and a single blue photoreceptor on the left side of his face. In addition to translating Nautila, the droid had a facial recognition system capable of identifying dead bodies, and a silent mode that could be toggled on and off via voice commands. He was a stickler for rules, consistently reminding his master of the bounty's terms during their mission on Batuu, as well as property regulations while on Eriadu.
Nine-Four-El made his debut in the first issue of Star Wars: Bounty Hunters, a comic book series penned by Ethan Sacks, illustrated by Paolo Villanelli, and published by Marvel Comics on March 11, 2020. His name was first revealed in the second issue, also written by Sacks and released on March 25, 2020.