The Mirialan Padawan to Luminara Unduli, Barriss preferred learning and studying the ancient Jedi texts in the Temple to being in the midst of war. A bit older than most Padawans, she follows everything her Master says to the letter, without question. So when she must work together with the young and impetuous Ahsoka in the middle of a battle, she must use all her training to survive the war and Ahsoka's extremely forward nature.
Luminara is a strict instructor, and she herself demands a strict discipline to the Jedi Code. Luminara is pleased with Barriss's progress, though she is not one to overly praise her studious Padawan.
Compared to Barriss, Ahsoka is downright rebellious. Tano is not above backtalk to her Master, Anakin Skywalker, something that struck Barriss as disrespectful and unbecoming of a Jedi. As she got to know Ahsoka, however, Barriss grew to appreciate her honesty and her adventurous spirit.
Barriss was part of the Jedi task force sent to rescue a captive Obi-Wan Kenobi in the confrontation that turned into the first Battle of Geonosis. Later, she was an important part of a Jedi team tasked with destroying a Geonosian droid factory during the Clone Wars.
After successfully destroying Poggle the Lesser's droid mill, Barriss was infected by a Geonosian brain-worm. The parasitic annelid crawled into her nostril and made her part of the Geonosian hive mind controlled by Queen Karina the Great.
The ongoing conflict of the Clone Wars demands much of the Jedi Order. Padawan learners are given the battlefield rank of commander, leading armies of clone troopers on distant battlefields far from the Jedi Temple.