Flanx grew up on the rocky world of Drahgor III, where his flock ran a fuel refinery that extracted fuel from the depths of the planet. Flanx had a cousin named Flix, whom he got on well with as children. Later, Flix came to regard their homeworld as backward and aspired for a career as a cantina singer. This caused friction between the two cousins, with Flix leaving under acriminous circumstances. Flanx vowed that Flix would one day return grovelling.
Following the retirement of Uncle Floog, Flanx inherited ownership of fuel refinery. Disregarding Gozzo legends warning against delving into the core of the planet, Flanx introducing deep core drilling operations. These activities disturbed the karnex dragons which dwelled in the depths of Drahgor III. Flanx regarded these legends as superstition that got in the way of profit.
Ultimately, Flanx and Flix's paths would cross again following the events of the Hosnian Cataclysm, which triggered the First Order-Resistance War. Following the Battle of Castilon, the Colossus space station had fled into deep space, eluding the First Order. With the Colossus running short on fuel, Flix accompanied his partner Orka, Kazuda Xiono, Torra Doza, and CB-23 on a mission to purchase fuel from the Flix flock's fuel refinery. By that stage, Flix had settled into life at the Colossus, running a repair shop called the Office of Acquisitions.
Upon meeting Flix, Flanx treated his cousin with contempt, mocking Flix for not following in the family business. Flanx also boasted that he was now in charge of the family's fuel refinery operations. He also rebuffed Flix's plea for fuel, stating that the flock had had made a profit from deep-core oil drilling. The revelation that Flanx was conducted deep-core drilling operations horrified Flix but Flanx dismissed his concerns as superstition.
After an apparent tremor disabled one of the flock's drillers, Kaz managed to convince Flanx to give them fuel in return for helping to restart the drill. Flanx accepted the offer but demanded that Flix and the others accompany Kaz and him down into the depths of Drahgor III.
Flanx and the offworlders descended down the depths of Drahgor III in a lift. During the journey, Flanx dismissed Flix's concerns about the karnex dragons as superstition and claimed that the planet was barren. After Kaz and Torra noticed some movement in the fog, Flix suspended the lift's descent, rightfully believing that a karnex dragon was around. The karnex dragon dislodged some rocks, causing the lift to descend out of control into the depths of Drahgor III.
During the descent, Torra and Orka were separated from the rest of the group. Before the lift carriage crashed into the ground, Flanx and the other passengers managed to jump out of the lift. Flix, Flanx, and CB-23 landed on one side of the ridge while Kaz landed on the side. The two groups were separated by a deep chasm. While Torra and Orka climbed up the shaft to get a shuttle to pick up the others, Flanx and the others traveled through the depths of the planet to find the deactivated drill.
While continuing their search for the drill, Flanx continued to argue with his cousin. He blamed Flix for causing the crash. Flix believed that the dragons were causing the tremors while Flanx continued to attribute the tremors to earthquakes affected the stabilizers. After some traveling, the two groups convered on the inactive drill. Kaz reported that he had sighted a dragon but Flanx refused to believe him. They managed to fix the drill but its drilling drew the attention of a karnex dragon.
The karnex dragon attacked the site, using its massive tail to topple the drill. Following a brief struggle, Flanx was kidnapped by the dragon, which dragged him back to its lair. Flix, Kaz and CB-23 pursued the dragon into its cave and managed to rescue Flanx from the karnex dragons. The family of karnex dragons pursued them to the drilling site where the group made their stand.
After realizing that the dragons had poor eyesight and could not stand bright lights, Flanx and the others used the blast lights to force the dragons back into their cave. They were joined by Torra and Orka, who arrived in a shuttle. Flanx used a drill to bury the karnex dragons under rock, separating them from their prey. Flanx apologized to Flix for not believing him and stated that he wanted them to be friends again. Flix accepted his olive branch and the group returned to the surface.
Upon returning to the surface, Flanx convinced the rest of his flock to cease deep core drilling since they were disturbing the karnex dragon's natural habitat. Flanx also gave Flix and his friends enough fuel to fill two giant tanks of fuel to thank them for saving his life. Flix and his friends departed for the Colossus on amicable terms with Flanx and the rest of the flock.
Flanx was a male Gozzo with black eyes and white feathers. He was an ambitious manager of his family's fuel refinery and sought to make profits through deep core drilling. Flanx and his cousing Flix were close friends during their childhood. However, their relationship was strained by Flix wanting to becoming a cantina singer and objecting to deep-core drilling. Flanx was dismissive of Flix's aspirations and regarded his belief in the existence of karnex dragons as "childlike" superstition.
As an adult, Flanx was obsessed with making profit from the fuel reserves beneath his family's fuel refinery. His greed led him to drill deeper, disrupting the natural habitat of the Karnex dragons. Ultimatly, Flanx was forced to repair his relationship with his brother Flinx who saved his life during a mission to restart a disabled drill. This adventure forced Flanx to accept that the Karnex dragons were real and to appreciate his cousin. As a result, Flanx reconciled with Flix, giving him the fuel that the Colossus needed. He also came to respect the deep core as the domain of the karnex dragons and abandoned deep-core drilling.
Flanx first appeared in the Star Wars Resistance episode "From Beneath," where he was voiced by Paul F. Tompkins. Tompkins recorded the role of Flanx back in Summer 2018, around the same time he appeared as the "toy Yoda" salesman in the 100th episode of The Star Wars Show.