Czethros, operating in 24 ABY, held a leadership role within the Black Sun organization. His face remained hidden behind a visor, and he possessed a cybernetic eye, singular in nature, that emitted a red glow. Furthermore, Czethros was characterized by his green-colored hair.
Prior to 24 ABY, Czethros, who worked as a bounty hunter, had pursued Han Solo, but a clever maneuver by Solo resulted in Czethros being sent to the spice mines of Kessel. The Black Sun crime syndicate had diminished in influence following the demise of Prince Xizor during a skirmish above Coruscant in 3 ABY, suffering from internal conflicts and maintaining a discreet presence for several decades. Nevertheless, they were actively attempting to infiltrate the New Republic by embedding cells within important political, economic, and military institutions.
In 24 ABY, following Zekk's victory in the Blockade Runners Derby, Czethros encountered Han Solo and his two offspring, Jaina and Jacen, along with their Academy peer, on Ord Mantell. Despite presenting himself as a legitimate businessman, Czethros orchestrated an ambush by Chameleon creatures serving Black Sun and arranged for his undercover operative, Anja Gallandro, to "rescue" them. Anja, though not a Jedi, wielded a lightsaber and relied on spice to amplify her senses, a supply controlled by Czethros to maintain her addiction.
Subsequently, aboard the Millennium Falcon, Anja accused Han Solo of her father's death. However, Han sowed seeds of doubt in her mind by aiding in the resolution of a 25-year-long civil conflict on her remote homeworld of Anobis, where Solo negotiated a truce between the warring factions. This caused Anja to question her animosity towards Solo, prompting her to join the Solo twins and their companions at the Jedi Praxeum to explore her latent abilities.
When the Solo twins and their companions, Tenel Ka and Lowbacca, visited Cloud City to experience the new SkyCenter Galleria amusement park owned by their acquaintance Lando Calrissian, Czethros orchestrated the murder of Cojahn, a business associate of Lando. This aroused the suspicion of the four Jedi, leading them to uncover Czethros's true identity and his scheme for galactic dominance during an expedition in the lower levels of Cloud City. However, Czethros evaded capture by deploying several Ugnaught Black Sun mercenaries to ambush them.
The four Jedi survived and successfully alerted the authorities to Czethros's threat to the galaxy. Consequently, Czethros became a wanted man by the New Republic. Nevertheless, leveraging his connections, he managed to evade capture once more and went into hiding. Unfortunately for Anja, she realized that without Czethros, her spice addiction would be left unfulfilled. Anja then commandeered an Academy vessel and journeyed to the ocean world of Mon Calamari, hoping to find a hidden stash of spice buried beneath the planet's frozen ice cap.
Czethros had also established cells on the spice-mining world of Kessel and nearly assassinated Nien Nunb, Calrissian's longtime Sullustan shipmate. Aware of the danger, Nien Nunb requested assistance, which arrived in the form of Jaina Solo and Lowbacca. However, due to the sleeper cells, Czethros and a force of Black Sun mercenaries seized control of Kessel. During the conflict, his agents captured Nien Nunb, though Jaina and Lowbacca managed to escape.
Meanwhile, at the resort city of Crystal Reef on Mon Calamari, Anja, aided by her Jedi companions Jacen, Tenel Ka, and Zekk, confronted her spice addiction and her hatred of Han. Together, they destroyed Czethros's spice cache on Mon Calamari.
Back on Kessel, Czethros intended to transmit a signal to activate the sleeper cells he had implanted in positions of power within the New Republic. However, Jaina and Lowbacca thwarted his plans by destroying the transmitter before Czethros could send his signal. They also liberated the prisoners and assisted in defeat of the Black Sun mercenaries. Rather than be captured, Czethros plunged himself into a vat of carbonite and was instantly flash-frozen. However, he was later recovered and taken into New Republic custody. Chief of State Leia Organa Solo oversaw his thawing and interrogation. Despite his lack of cooperation, a strategy devised by Anakin Solo led to the discovery of the Black Sun moles in their strategic positions, resulting in the downfall of the crime syndicate.