Vydel Dir'Nul, a Jedi Knight of Human female descent, lived during the era of the Clone Wars. One month prior to the start of the Clone Wars, the Jedi Council tasked Dir'Nul with the role of protector for a certain individual. During this assignment, Dir'Nul developed feelings for Ash B'risko, a pilot of a freighter, and they began a romance. However, she later discovered B'risko with a Twi'lek woman in his arms. In a fit of rage, Dir'Nul killed both B'risko and the Twi'lek, and in doing so, unknowingly gave rise to the male Dark Jedi persona of Kardem, whom she mistakenly believed to be a separate being. After the double homicide, Dir'Nul was unaware that she suffered from dissociative identity disorder or that she was responsible for B'risko's death.
At the onset of the Clone Wars, Dir'Nul declined the position of general within the Grand Army of the Republic, instead dedicating her efforts to hunting down Kardem. After traveling to the planet called Perilious, she, acting as Kardem, murdered three more Twi'lek women. Six months later, while investigating these murders as Dir'Nul, she encountered a male Jedi, whom she wrongly identified as Kardem. After the Jedi bested her in a lightsaber battle, Dir'Nul switched to the Kardem personality and attacked him using Force lightning.
The Jedi revealed that the Council had dispatched him to apprehend Dir'Nul, either dead or alive, for her crimes and subsequently attempted to eliminate her. However, she anticipated the attack, eliminated the Jedi. Following his death, Dir'Nul reverted to her original self and believed him to be another victim of Kardem.
Eventually, a reward was offered for the capture of her Kardem alter ego, leading to her capture by Feskitt Bobb, a Mandalorian bounty hunter.

Vydel Dir'Nul, a Jedi Knight of Human female origin, served during the concluding years of the Galactic Republic. In 22 BBY, the Jedi Council assigned Dir'Nul to the role of bodyguard for a specific individual. During this protective mission, she developed romantic feelings for Ash B'risko, a pilot operating a freighter.
She entered a romantic relationship with the pilot, a decision that violated the tenets of the Jedi Code. However, she later discovered B'risko in an intimate embrace with a female Twi'lek dancer. Dir'Nul murdered both B'risko and the Twi'lek, and in doing so, created the personality of a male Dark Jedi named Kardem, whom she believed to be a different individual. As Kardem she began to murder female Twi'leks while, in her original personality, she began tracking "him" to avenge his victims, especially Ash.
Following the Clone Wars—the Republic's armed conflict with the Confederacy of Independent Systems—which commenced at the First Battle of Geonosis, Dir'Nul refused to rejoin the Jedi and accept a position as a general in the Republic Army. Dir'Nul buried B'risko and began tracking Kardem in the Outer Rim, killing two more Twi'lek females while acting as the Dark Jedi. By the time she arrived on the planet Perilious—which was known for its Twi'lek slave tradings—Dir'Nul had slain three more Twi'lek females as Kardem.

Six months later, as Dir'Nul investigated the murders of the three Twi'leks, a robed man wielding a lightsaber revealed himself to her, and she attacked him, assuming he was Kardem. After a brief lightsaber duel, the man gained the upper hand and defeated Dir'Nul. As he informed her that he was going to bring her back to the Jedi Council for her crimes, Dir'Nul reverted to the Kardem personality—who was unaware that he was Dir'Nul—and unleashed bolts of Force lightning against her attacker.
After the Jedi used Dir'Nul's name while pleading with her to stop attacking him, Kardem told the man he was going to kill him. The man revealed that he was a Jedi and that he had been tracking Dir'Nul for six months. The Jedi ignited his lightsaber and used the Force to throw it at Dir'Nul, determined to bring her to the Council dead or alive. However, Dir'Nul, who was still mentally Kardem, used the Force to stop the lightsaber midflight and attacked the Jedi with more lightning. As Kardem was torturing the Jedi, he claimed that he did not know Dir'Nul and threw the lightsaber back at the Jedi, cutting him in half.
Dir'Nul reverted to her original personality following her attacker's death and was shocked to learn that Kardem had killed a Jedi. She vowed to stop Kardem no matter what it took, unaware that she was the one who had actually committed the crime. A bounty was eventually placed on Dir'Nul's split personality of Kardem. The serial killer was captured by the Mandalorian bounty hunter Feskitt Bobb.
As a Human female, Vydel Dir'Nul dedicated herself to the Jedi Order as a Jedi Knight. During her assignment to safeguard an individual, she fell in love with the pilot Ash B'risko, willingly defying the Jedi Code. Upon discovering B'risko in the arms of a Twi'lek dancer, Dir'Nul was consumed by anger, leading her to immediately kill both of them. During the act of murdering B'risko and the Twi'lek, Dir'Nul unknowingly manifested an alter ego in the form of a male Dark Jedi named Kardem. After burying B'risko, driven by a desire for answers and vengeance, she committed herself to capturing Kardem.

Following the outbreak of the Clone Wars, Dir'Nul expressed no interest in fighting for the Republic's politicians, whom she perceived as greedy and self-serving, thus refusing to serve as a Jedi General. Neither Dir'Nul nor Kardem was aware of the other's existence. During her pursuit of Kardem, she continued her vendetta against Twi'lek females, violently murdering them as Kardem. After she reverted to her normal personality, Dir'Nul would hear Kardem's voice, which would degrade Twi'leks and taunt her. After she was defeated in lightsaber combat by the male Jedi, she adopted the Kardem personality and began torturing him. When Kardem killed the Jedi, Dir'Nul reverted to her original personality and vowed to stop Kardem, regardless of how long it took and no matter what she had to sacrifice.
Dir'Nul possessed the ability to manipulate objects using the Force; she employed this ability against the male Jedi dispatched by the Council to apprehend her. When Dir'Nul shifted her personality to that of the serial killer Kardem, she gained access to dark-side Force powers, including Force lightning. She utilized this power against numerous Twi'leks and against the male Jedi. However, during her duel with the Jedi sent to apprehend her, he gained the upper hand, noting that she had allowed her lightsaber combat skills to deteriorate. After the Jedi threw his lightsaber at her, she was able to stop it midflight. Dir'Nul herself wielded a lightsaber containing an orange crystal.
The characters of Vydel Dir'Nul and her split personality, Kardem, made their debut in the short comic "Dark Journey," featured in Star Wars Tales 17 and authored by Jason Hall. The comic's artwork was created by Ben Templesmith. The story was later compiled into a trade paperback version and republished in Star Wars Tales Volume 5. Plausible stories in Star Wars Tales 1–20 were deemed S-canon until referenced in a non-Tales source, at which point the subject matter was elevated to C-canon status. Dir'Nul was first referenced outside Tales in the article The History of the Mandalorians, written by Abel G. Peña and published in Star Wars Insider 80. Her split personality of Kardem was used as part of the background for the Mandalorian Feskitt Bobb. Her appearance in The History of the Mandalorians elevated Dark Journey to C-canon. Dir'Nul later received an entry in The Complete Star Wars Encyclopedia.