Travell is a member of the highly advanced Tollan race and High Chancellor of the Tollan Curia, their highest ruling body. Travell was a staunch defender of the Tollan's highest law: they do not share their technology with less advanced species.
She administrated the Triad (as a judge) of Skaara and Klorel. When SG-1 approached her with evidence that Zipacna's Jaffa were targeting the Tollan Ion cannons, she believed it was impossible that Zipacna was planning to attack. When Zipacna did attack and Teal'c with the help of Lya was able to cloak one of the Ion cannons and destroy the Ha'tak, she was grateful. (SG1: "Pretense")
When a team of rogue NID personnel began to steal Tollan technology, she approached Stargate Command to deal with the problem. She then took part in the ruse of Colonel Jack O'Neill stealing a piece of technology so he would be approached by the rogue group. (SG1: "Shades of Grey")
When Anubis's forces bore down upon Tollana (commanded by Tanith, who came in a ship with new shields impervious to the Tollan defensive weapons network), Travell and the Curia were forced to strike a deal with the Goa'uld. In exchange for the survival of the Tollan people, they would create advanced weapons of mass destruction, capable of bypassing even the Iris protecting Earth's Stargate.
But SG-1 and her associate, the Tollan Narim, learned about Travell's plans. For the sake of Narim and the rest of the galaxy, Narim used the Tollan Ion cannons to break the bargain with the Goa'uld. Tanith attacked, placing Travell and the rest of her people in the midst of a war they could not win. Travell and the Tollans are presumed dead. (SG1: "Between Two Fires")