Merrin was a Dathomirian Nightsister who lived on her homeworld of Dathomir during the Imperial Era. A survivor of General Grievous' massacre of the Nightsisters during the Clone Wars, Merrin encountered the Jedi Master Taron Malicos after he crash-landed on Dathomir following the execution of Order 66 in 19 BBY, which called for the extermination of all Jedi. Malicos fell to the dark side of the Force, and wishing to learn the Nightsister's magick, he manipulated Merrin through lies that the Jedi were responsible for her losses and false promises to help her avenge her fallen friends, sisters, and mothers.
When Cal Kestis visited Dathomir in search of the Tomb of Kujet and Malicos asked the former Jedi Padawan to join him, Merrin realized Malicos was deceiving her. She used the Chant of Resurrection to attack both men, but Kestis eventually returned to complete his mission. Although Merrin was reluctant to fight alongside a Jedi, Kestis reassured her that he was on her side by sharing the story of his own grief-stricken past and handing his lightsaber to her. She told him about seeing her people killed by an armored warrior brandishing a lightsaber. Affirming that they were both survivors, Merrin and Kestis worked together to defeat Malicos, and the Nightsister subsequently joined Kestis' crew aboard the Stinger Mantis in their quest to restore the Jedi Order and fight the Galactic Empire.
After several years of evading and battling the Empire, the Mantis crew parted ways over irreconcilable differences. Merrin traveled the galaxy alone, righting wrongs where she could. This led to her becoming involved with the Hidden Path, which sought to save Force-sensitives being hunted by the Empire. She reunited with Kestis during the latter's hunt for hidden world of Tanalorr and rejoined the Mantis crew, hoping the obscure planet could be a refuge for the Path. During this mission, she and Kestis became romantically involved. She and Kestis fought together and succeeded in recovering the Abyss compass necessary to reach Tanalorr, vowing to make the planet a haven for those hunted by the Empire.
