Serving both the Jedi Order and the Galactic Republic, Jedi Master Kast Fulier, a male Human, operated in the decades preceding the Clone Wars. Fulier, together with his Padawan, Etain Tur-Mukan, was given the assignment to investigate the oppression occurring on the planet Qiilura at the hands of the Trade Federation. While Tur-Mukan ultimately completed their mission, Master Fulier perished on the planet.
Kast Fulier demonstrated that he was Force-sensitive when he was very young, and as such, he underwent training at the Jedi Temple's academy on Coruscant. Eventually, a Jedi Master selected him to be their Padawan. After years of study, and the construction of his blue lightsaber, Fulier successfully completed his Trials of Knighthood and was made a Jedi Knight by the Jedi High Council. He served the Order for numerous years, developing a reputation for bending the rules, similar to Master Qui-Gon Jinn. After becoming a Master himself, Fulier took on Initiate Etain Tur-Mukan as his apprentice.
In 22 BBY, the High Council became aware of the growing presence of the Trade Federation on Qiilura and suspected their involvement in supporting the Confederacy of Independent Systems during the Separatist Crisis. The Council dispatched Fulier and his Padawan Tur-Mukan to investigate, with particular interest in the roles of the infamous scientist Ovolot Qail Uthan and the Mandalorian mercenary, Ghez Hokan. Operating undercover on the agricultural world, the Jedi attempted to infiltrate small farming communities, but they were unsuccessful because the farmers were loyal to Hokan due to his bribes. Eventually, the Jedi were handed over to the Mandalorian, but Tur-Mukan managed to escape into the countryside. Fulier was brought to the Trade Federation stronghold for interrogation, where Hokan used Fulier's own lightsaber to kill him after the Knight refused to provide information.
His Padawan survived him, and she eventually received aid on Qiilura in the form of Republic commandos. The commandos raided the Trade Federation facility, killing Hokan and apprehending the scientist he was protecting. RC-8015, a commando, recovered Fulier's lightsaber from Hokan's body and gave it to Padawan Tur-Mukan after the Qiilura incident. Although Tur-Mukan died during the early stages of the Great Jedi Purge, her loyal commandos recovered Fulier's lightsaber and passed it on to her secret son, Venku Skirata.
Those who knew Fulier well observed that he was one to never step down from any challenge. While they were on Qiilura, Fulier used all of his and his Padawan's bacta spray to assist the villagers, choosing not to keep any for themselves. He was taken into captivity while attempting to teach one of Hokan's thugs a lesson for mistreating the townspeople. Fulier would not allow any difficult or impossible situation from stopping him from doing what he thought was right, no matter what the repercussions might be.