Terlyn lived on Onderon, a Inner rim planet within the Galaxy. Terlyn was married to a member of the Council of Lords who supported Queen Talia during the Onderon Civil War. She was also the parent to a son and a daughter and lived together with them in Iziz, the capital city of Onderon. Prior to Meetra Surik's mission to Onderon, Terlyn's husband attempted to assassinate General Vaklu, but was killed in the process. After her husband's death, Terlyn hoped to leave Onderon with her children. However, due to the ongoing unrest, she was unable to acquire a starport visa. Terlyn approached spacers who passed through the Merchant Quarter of Iziz, hoping to find one who had a spare open starport visa.
When attempting to visit Onderon, the Jedi Exile Meetra Surik was fired on by Vaklu's forces and crashed on Dxun, one of Onderon's moons. Hoping to meet Jedi Master Kavar, Surik gained the assistance of the Mandalorians, and arrived in Iziz with Mandalore the Preserver. When Surik passed through the Merchant Quarter, she met Terlyn. Terlyn explained her plight to Surik, who agreed to help. During her time on the planet, Surik came into possession of a open starport visa, and gifted it to Terlyn. After profusely thanking Surik, Terlyn left Iziz with her children.
Terlyn appeared in the 2004 roleplaying game Star Wars: Knights of the Old Republic II: The Sith Lords, developed by Obsidian Entertainment. The game was a sequel to the 2003 game Star Wars: Knights of the Old Republic, developed by BioWare.
The Exile can tell Terlyn to get out of her way when they first meet, resulting in dark side points. However, if talked to again, Terlyn will still beg for a starport visa. If she is not given a visa by the time he Exile meets Kavar and leaves Onderon, she does not receive one. On the Exile's return to Onderon, Terlyn does not appear.