T'un functioned as a Jedi Master, giving service to both the Jedi Order and the Galactic Republic throughout the final centuries of the Republic's dominance of the galaxy. Approximately around the year 94 BBY, T'un was given the responsibility of overseeing all holographic data files pertaining to Jedi Initiates inside the Order. As a member of the Jedi High Council, access to these records was restricted, requiring explicit authorization from T'un or another Council member.
By 44 BBY, T'un had lived for hundreds of years, gaining significant wisdom and knowledge. In that year, some of the files under his care were stolen, but Jedi Master Qui-Gon Jinn successfully retrieved them. Each year, T'un was assisted by two student volunteers in managing the files within his office, but these volunteers were not permitted to be in the filing office unless the Jedi Master was present.
T'un's initial mention occurred in Jedi Apprentice: The Uncertain Path, which is the sixth book in the Jedi Apprentice series. Jude Watson authored The Uncertain Path, and it was released in 2000.