Arden Lyn was a female Human and master of Teräs Käsi who belonged to the Followers of Palawa. This ancient Dark Jedi, along with her fellow Palawans, joined the Legions of Lettow upon the advent of the First Great Schism between Force users, and became the lover of Xendor, head of the Legions. When Xendor was killed during the conflict, Lyn ascended to leadership of the Legions, although she was confronted by Jedi Master Awdrysta Pina. Lyn defeated Pina with a powerful Kashi Mer talisman, but the Jedi Master was able to stop Lyn's heart before being destroyed, sending the martial artist into a Force trance.
A destructive individual, Lyn and her lover Xendor wreaked havoc and tumult throughout the galaxy during the Age of Uncertainty. After her reawakening by the Inquisitors, Lyn's mind was highly unstable, and she had been driven insane. When Darth Sidious recruited her to his cause, he appealed to her love for the long-dead Xendor, promising to bring him back to life. Although initially swayed by Sidious's words, Lyn eventually came to the realization that the Emperor had tricked her, and at the first opportunity, turned on him. Lyn was also adept at recruiting students to her cause, as she demonstrated after turning rogue. When faced with a specific opponent to hunt down and confront, Lyn looked for weaknesses to exploit.