Tahiri Veila was born on Tatooine, raised on a moisture farm before her family was slaughtered by Tusken Raiders. A kind Tusken named Silven took her in, raising her in the tribe before she was found by Jedi Master Tionne, and brought to the Jedi Academy on Yavin IV. She became best friends with Anakin Solo, also new to the Academy himself.
The pair would engaged in many small conflicts during their time in the Academy, including saving captive children in the Golden Globe and recovering Obi-Wan Kenobi's lightsaber. They also met Ikrit, a rabbit-like Jedi Master, who was a former apprentice to Jedi Master Yoda before he disappeared 400 years ago on Yavin, himself in search of the Golden Globe.
Yuuzhan Vong War
Anakin would leave the Academy, leaving his own friend behind. Many years later, at sixteen - Tahiri herself being thirteen-fourteen - he returned when the Academy was about to be assaulted by the Yuuzhan Vong and their allies, the Peace Brigade. She was both happy that he returned, and greatly hurt that he never contacted her after he left. The two, along with Tionne and many students at the Academy, escaped the initial assault by the Peace Brigade, at the cost of Ikrit - who sacrificed himself to give the students time to escape.
Unfortunately, Tahiri would be captured during a skirmish with the Peace Brigade. When the Yuuzhan Vong and their Shapers - along with Mezhan Kwaad and Nen Yim - arrived, they transformed the Jedi Academy into their base. These Shapers were tasked with finding the source of a Jedi's power - the Force - and how it worked. After much research and experimentation, they attempted to brainwash Tahiri into becoming one of them, inflicting horrific, torturous methods to transform her - mind and body.
Anakin eventually saved her after going through many ordeals himself to return to the Academy, bringing her mind back to herself. However, much damage was done. From that day forth, she was hardened and angry, losing much of herself back on Yavin. She also bore the scars from her ordeal, namely three claw-like stripes on her forehead.
She fought beside Anakin during the Mission to Myrkr to stop a plot by the Vong to clone Vornyx - creatures who hunt and feed on Force Sensitives. It was on that mission that Anakin and Tahiri discovered their love for one another. Unfortunately, this love never went beyond that: Anakin Solo was killed during the mission, and his brother, Jacen Solo, was captured by the Vong.
Second Galactic Civil War
Over a decade after the Yuuzhan Vong War, Tahiri was still mourning over the loss of Anakin. Jacen Solo, who had turned to the dark side - partly to Jacen's own torture at the hands of the Yuuzhan Vong, something Tahiri could relate to in him - and became Darth Caedus, desired a new apprentice. He manipulated Tahiri with his use of the technique known as Flow Walking, an ability that allows him to go back in time and watch events. He brought Tahiri back to Myrkr, and allowed her to kiss Anakin before he died - something she always regretted not doing.
Under Caedus, Tahiri was manipulated into committing countless dark acts, including torturing Lon Shevu to death, attempting to seduce Ben Skywalker, and killing Gilad Pellaeon.She served him with the promise that he would one day change time and prevent Anakin from dying. However, this was not possible and he knew it. Flow Walking only changed the user's own perception of events and allowed them to interact with the past, but changing time was not possible. When she discovered this, she was enraged. During her final mission for Caedus, she fought Ben Skywalker, flailing around with her blade, almost hoping Ben would kill her on the spot.
She survived, leaving the Order after Caedus' death at the hands of his twin sister, Jaina Solo.
Tahiri was very spirited and adventurous. As a child and even into adulthood, she walked around barefoot, avoiding footwear whenever possible, because she always hated the confining wraps of the Sandpeople. Tahiri would be forced to grow up quickly, becoming hardened by the ordeal and torture inflicted upon her by the Yuuzhan Vong.