When Crymsin accepted her role as padawan, she became a good friend to Ahsoka Tano. Crymsin and Ahsoka shared a lot, and trained together with their masters. After her master, Kassa Pon was killed by the bounty hunter, Aurra Sing on 30 BBY, Crymsin was heart broken and angry about her master's death. She swore revenge for her master's death until she was calmed down by Ashana who became her second master.
For years, Crymsin trained very well with her master. She remained friends with Ahsoka while she made friends with Orie, Jasper, Kellavine, and Ven Kital. Crymsin sometimes flirted with Ven, and she shared a secret relationship with him. On 24 BBY, Crymsin became a Jedi Knight and took Milly Oria as her apprentice. However, she did not remain with her padawan for long. In the city of Coruscant, Crymsin and Milly went on a mission to hunt down a criminal. They were separated unil Milly was kidnapped by Aurra Sing. Crymsin kept on looking for her until she found her body in the alley. Crymsin sensed that Aurra Sing did this and went on the hunt to avenge her padawan's death.
Following her scent to the bar, Crymsin looked around until the bounty hunter was behind her. Crymsin turned and ignited her lightsaber before Aurra could shoot her. Aurra ran out, but Crymsin followed her and fought her on top of a platform. Crymsin fought against the dangerous bounty hunter, but Aurra made a kick, and threw her off the platform. Crymsin survived the fall, and held to a broken pipe.
After failing to stop Aurra, Crymsin returned to the Jedi Temple to inform her padawan's death. Lying in tragedy, Ven came to her and made her feel happy. Crymsin ad Ven shared their secret relationship and continued to serve the Order. After Milly's death, she took Elena Kita as her new padawan.
The Petranaki arena
During the Petranaki arena battle, Crymsin, along with Elena, Ven, and Aidan fought on top while Orie, Suma, Kellavine, Tisha, Jasper, and Adam were down on the floor, battling many battle droids. When Crymsin fought brave, her padawan was shot down by a couple of battle droids, and Crymsin destroys them in rage. Ven tried to save her, but he was shot behind by a battle droid. Crymsin tried to avenge her lover's death, but she fled the scene when the surviving Jedi were rescued. Crymsin fled Geonosis and returned to Coruscant.
Losing everything, Crymsin fell to the dark side of the Force and joined the Believers, a Sith cult that was based in the Cularin system. When a year passed during the Clone Wars, Crymsin traveled to the planet Caarimon to release a virus into the planet's atmosphere and kill its indigenous species, the Caarites.
Redemption and Death
Behind the scenes
In The Star Wars Clone Wars, Crymsin Ost is portrayed and voiced by American actress and model, Megan Fox.