Born on a starliner in deep space, Barriss was brought to the Jedi Temple, where she would spend her early years in study of the Force. A loyal Padawan to the powerful Jedi Master Luminara Unduli, Barriss spent most of her time by her side, whether during important meetings with Supreme Chancellor Palpatine or in combat such as the Battle of Geonosis. When she reached sixteen years of age, she built her first lightsaber.
Shortly before the outbreak of the Clone Wars, Barriss and Luminara—along with Obi-Wan Kenobi and his Padawan Anakin Skywalker—were sent to Ansion to prevent the government of the planet from voting to join the Separatists. The mission was important because, although Ansion itself was not very important, if it chose to join the CIS then many other planets would follow. However there were many beings set upon making sure the Jedi's mission was a failure, one of them being the Hutt Soergg who had been hired by Shu Mai to stop them.
The Jedi were allowed to talk to the Unity of Community. Luminara made a deal to the Unity: The Jedi would put an end to a conflict between the 'city-folk' and the Alwari natives if Ansion agreed to stay within the Galactic Republic and abide by their rules. The conflict was over land, so Luminara also said that they would get the Alwari to agree to share half or more of their land. The Unity agreed and the Jedi left. Before the Jedi could set off on their mission, two Alwari named Kyakhta and Bulgan were hired by Soergg to capture one of the Padawans. They caught Offee and held her prisoner, however both the Alwari were mentally impaired and so Offee managed to gain their trust by healing them. After this Kyakhta and Bulgan agreed to act as guides for the Jedi, as to secure the treaty with the Alwari, they would first have to find them. The Jedi left the city shortly after, riding suubatar. They shortly had more trouble with gairks in a stream but overcame this as well.
Eventually the Jedi managed to meet with the Yiwa—an Alwari tribe. At first, the Yiwa were mistrustful of the Jedi, and the Highborn, Mazong, requested that they each perform a display, and that after this, the Yiwa would decide whether or not to tell the Jedi where the overclan was. Barriss gave a display of acrobatics, which greatly impressed the Alwari, as well as Anakin. After the other Jedi had given their presentations, the Yiwa told them where the overclan could be found, and they set off again.
Later, the Jedi came across a group of Gwurran. After throwing a party for them, the Jedi left, but Tooqui—a Gwurran—came with them. It was shortly after that the Jedi met with a tribe of traders named the Qulun. The Jedi were offered food and accepted into the tribe, however the tribe leader Baiuntu was working for Soergg, and managed to capture the Jedi. Luckily, Tooqui got away, and shortly after rescued the six of them.
The Jedi soon came upon the Borokii overclan and gave their proposal. The Borokii agreed but only on the grounds that the Jedi settle a conflict that existed between the Borokii and the Januul, another overclan. The Jedi agreed and ultimately managed to settle the conflict diplomatically. They then returned to the city where they were again delayed by Soergg, who had hired thugs to dispatch them. However the Jedi managed to make it to the Unity, which was in the process of voting. Due to the fact that the Jedi had settled the border dispute, the Unity voted to stay within the Republic and the Jedis' mission was a success.
When Barriss and Luminara returned to Coruscant, they were dispatched by Mace Windu to Geonosis as part of the stike team to rescue Obi-Wan, Anakin, and Padme Amidala. Although Barriss was not in the final circle that was picked up by Yoda's gunships, she did find a way out of the Petranaki arena along with Jedi Knight Pablo-Jill.
Later on during the Clone Wars, Barriss and Luminara ventured to the ice-world Ilum. From this barren planet, the crystals needed in the construction of a lightsaber could be found. In a secret Jedi temple mine, Barriss built herself a new lightsaber with a crystal of her choice.
As she constructed her lightsaber, the location of the temple was compromised. Separatist chameleon droids had infiltrated the mines and placed explosive charges in the tunnels. Barriss and Luminara fought them off, but were trapped in the resulting cave-in using the Force to stop hold up the roof. This disturbance in the force reached Yoda and the diminutive Jedi Master rescued them.
While her Master guarded Nute Gunray on the Tranquility, Offee oversaw a mission to Geonosis .
Offee and her master were sent to the planet Geonosis to aid Jedi General Anakin Skywalker and his Padawan, Ahsoka Tano, in helping destroy the weapons factory, headed by Poggle the Lesser. Tano and Offee were sent under to the catacombs, while Skywalker and Unduli acted as decoys. The Padawans made it to their destination, however they had been spotted and were attacked by the new Confederate super tank, as well as Geonosians, and the bombs they had planted were removed while the two were distracted. Tano and Offee took control of the tank, and came to the conclusion that the only way to destroy the factory would be to use the tank's weapons to fire upon the reactor, even though they knew that they likely would not survive the explosion. They did not know about the shielding on the tank, though, which saved the two Padawans, but they were buried under a large amount of debris. Worried they would die from lack of air, Ahsoka pulled a power cell apart, activating her comlink so their masters could find them. Anakin picked up the signal, leading their Masters to rescue them from the debris.
Barriss and Ahsoka were transporting a supply ship to the Ord Cestus medical station. The Padawans decided to get some sleep but while Barriss could Ahsoka couldn't. Unknown to them, a clone trooper was leaving the Brain worm eggs to spread across the ship. While Ahsoka and Barriss were eating, two clones tried to kill them. Later in the ship they saw Trap trying to infect them. Barriss was forced to kill him.
After discovering that clones upon their ship where being controlled by Brain worms, Barriss and Ahsoka then separated. Barriss was heading to the engineering section to disable the ships engines when she walked into a trap set by the clones. She was unable to resist as the clones exposed her to a brain worm and succumbed to the worm's influence. When she found Tano, the two began to duel. Ahsoka tried to convince Barriss to resist being controlled, and somewhat succeeded as Offee told Ahsoka to "kill her" in order to ensure the worm's death. However, when the worm tried to flee Barriss' body and enter Ahsoka's directly, Tano sliced the worm in half, releasing Barriss.
During the Invasion of Coruscant, Offee commanded a squad of clone troopers in the fight against Separatist droid forces. In the underlevels of the city, her squad was overrun by battle droids, including the new C-B3 cortosis battle droids that were resistant to her lightsaber. Just in time, young Anakin Skywalker arrived at the scene and managed to push back the droid forces.
Afterward, Barriss was sent to the planet Drongar; her first mission without her master. Drongar was the home to a valuable plant, bota, which was a miracle cure for almost anything and for any race, prized by both the Galactic Republic and the Separatists. Barriss, a gifted healer, assisted one of the medical units on the planet. Unknown to her, a spy was sneaking around the camp and several corrupt Republic representatives were shipping off bota illegally for their own profit.
In a turn of events, she accidentally injected herself with bota, and the natural drug opened up the Force in new and powerful ways. Barriss found this quick way to power to be too addictive and knew that it would lead her towards the dark side of the force, but she resisted its luring pull. Once she had overcome the inner battle of resisting the dark side, she felt that she had earned the rank of Jedi Knight and General.
Barriss remained in partnership with her former Master until the end of the Clone Wars. Dispatched to Felucia to serve as a healer with her new Padawan Zonder, they were captured by Gossam Cammandos working for the Confederacy of Independant Systems and thrown in prison. They were later rescued by the Jedi Aayla Secura and Erika, as well as the clone trooper lieutenant Galle. It was later revealed that Presidente Shu Mai of the Commerce Guild had arranged to poison Felucia's water supply, and so Offee and Secura sought to save the planet.
Following lieutenant Galle, Offee took a squad to Har Gau while Secura and Commander Bly went to Niango. When Offee's group arrived at their site, they saw that the defenders consisted mostly of setients, rather than droids, and realized they could not simply blast their way into the center. Padawan Drake Lo'gaan, who had accompanied Secura to the planet enlisted Galle's help for his plan. In order for the Padawans to infiltrate the water planet, Zonder drew the attention of the Gossam Commandos, while Galle and the Padawans attacked, striking down the droids. The Padawans then detached from Galle's squad, moving into position near the center. Lo'gaan commed Galle and ordered him to activate the next phase of the plan, and Galle called for a retreat. The defenders pursued, leaving the way wide open for the Padawans to infiltrate the plant and stop the toxins.
As Galle fell back, Bly received an encrypted message from Coruscant, ordering him to execute Order 66, a contingency order that demanded the deaths of all Jedi. Galle and his squad rendezvoused with Offee, who was fighting off a number of battle droids. Galle came to a halt, and Offee ordered him to fire. The lieutenant complied; he ordered an AT-TE to open fire on Offee, killing her. As Offee died, lightyears away, her former master perished also.
When the Galactic Empire emerged, official records compiled by Sate Pestage stated that Offee and Secura were both executed because they were plotting to poison Felucia's water supply.