Born in the Outer Rim, Arlya was captured by the Zygerrian Slave Empire early in life and sold to the New Sith Empire. When she was ten, she was rescued by Karr Shadeez in a raid on a Sith camp. Sensing the Force in her, Karr took her as one of his first Padawans, helping her overcome her bitterness and anger and embrace the light side of the Force. She proved a skillful warrior against various dark side factions, surviving a lightsaber blow across the back of her neck and shoulder and decapitating her enemy. Karr knighted her in 1,392 BBY. She took a Padawan of her own not long after.
In 1,389 BBY, Arlya was present along with several other Knights when Shadeez journeyed to Gizer Battlestation to discuss an alliance with Admiral Herqilius Arstyn. She was protective of her comrade Rhosa Xei when Shadeez met with Tirien Kal-Di, who had been dispatched by the Council of Reconciliation to attempt to return Shadeez's faction to the Jedi Order. Afterward, Arlya volunteered to escort Tirien's Zygerrian Padawan, Narasi Rican, back to her ship. She considered it a challenge to herself, making sure she could overcome the emotional aftereffects of her time in slavery. She defended Narasi against insults from Republic soldiers, but became introspective afterward.
The following day, Arlya stood guard outside a meeting among Arstyn, Shadeez, and Kal-Di. When they agreed to sign an accord, Rhosa began to experience misgivings, which she attributed to a disturbance in the Force. While no one else in their group sensed anything similar, Shadeez ultimately sent Arlya, Farwel, and Jarkun'eir'saikal back to his flagship, the Crusader, to protect the fleet and their Padawans. As such, she was not aboard Gizer Battlestation when Arstyn and Shadeez were assassinated (and Rhosa was accidentally killed as well) by Alecto.
In late 1,387 BBY, over two years after Rhosa and Shadeez's deaths, Arlya contacted Tirien on Anaxes, asking his opinion of Jedi Master Argus Z'dar. The two arranged a meeting on Corsin weeks later, but when Supreme Chancellor Phnyong was assassinated and Tirien lost his Force powers due to Kai Latra's Sith poison, he missed the meeting. In 1,386 BBY, Tirien ran into Z'dar, now at the head of Shadeez's crusade, only to learn that Arlya had been one of the earliest casualties of Z'dar's campaigns.