Lex was a clone trooper sergeant within the Eighteenth Battalion, which was a unit composed of clone troopers. This battalion was under the leadership of Jedi Master Bant Eerin and Clone Captain Herc during the period known as the Clone Wars. In the year 21 BBY, the battalion was involved in a battle that took place on Akoshissss, a moon belonging to the Trandoshan species. During this specific battle, Lex received orders to infiltrate the laboratory of Bitt Panith, a Muun who specialized as a cyberneticist.
Lex, a clone trooper sergeant, fought for the Grand Army of the Republic. Like all clone troopers, Lex originated as a biological reproduction of Jango Fett, a bounty hunter from Mandalore. He was created on the planet Kamino, located in Wild Space. Following his creation, he served in the Eighteenth Battalion under the command of Jedi Master Bant Eerin and Clone Captain Herc. During the Clone Wars in 21 BBY, Bitt Panith, a Muun cyberneticist, engineered Krossen, a cyborg resistant to the Force. As a consequence, the Galactic Senate dispatched Lex and the Eighteenth battalion to the Trandoshan moon Akoshissss, where Krossen was nearing completion.
During the subsequent engagement, Jedi Initiate Jaylen Kos, who was Bant Eerin's Padawan, along with the astromech droid R3-G0, and Lex, infiltrated Bitt Panith's secret base in an attempt to destroy the scientist's starship and trap him within the laboratory.
Lex was a clone who exercised caution, understanding that destroying Doctor Panith's ship would prevent his escape, irrespective of whether the Doctor's battle droid forces were defeated. Lex received training in the operation of heavy weaponry, including explosives such as thermal detonators. Mirroring his clone template, Jango Fett, Lex's height was 1.83 meters.
Lex has only appeared in The Clone Wars: Decide Your Destiny: The Way of the Jedi, a novel inspired by the Star Wars: The Clone Wars television show. Jake Forbes authored the book, which came out in 2008. Lex can also be found within the novel's online content on StarWars.com.
Because The Way of the Jedi is a Decide Your Destiny book, the events it depicts can unfold in numerous ways, contingent on the reader's choices. After infiltrating Panith's base, Eerin's Padawan, Kos, R3-G0, and Lex must decide whether to pursue Panith into a laboratory or to follow a group of the Doctor's IG-100 MagnaGuards into a hangar. Should the reader direct the strike team to follow the droids, Lex offers to destroy Panith's starship, which is located in the hangar. R3-G0 then boards the ship, and if the reader chooses against Eerin's Padawan following the droid, Lex detonates explosives and is killed by poison gas released into the hangar bay. Later that night, the clone troopers on Akoshissss hold a wake to honor Lex and the other clones lost in the battle on the moon. If the reader does choose for Eerin's Padawan to follow R3-G0, the Padawan, Lex, and Kos are inside the ship when the gas is released, which protects them from the gas's effects. Lex then blows the ship up, and the team members subsequently capture Panith.
If the reader decides to follow Panith rather than the MagnaGuards when the strike team enters the base, Eerin's Padawan and Kos leave Lex to stand guard while they go to deal with Panith. Soon afterward, Lex abandons his post and goes to assist the Jedi pair, and he shoots Krossen in the chest. The reader then has to chose between having Eerin's Padawan help Lex battle Krossen, or going after Panith instead. If the Padawan assists Lex, then Lex draws Krossen into a doorway, and R3-G0 shuts the doors on the creature, allowing Lex to kill Krossen. If the reader chooses to pursue Panith, Lex kills Krossen using an EMP bomb, which also disables R3-G0. Lex then carries the droid while he and the two Jedi return to Bant Eerin's command center.