She became High Rhulain of Green Isle after an arduous quest. She grew up in Redwall Abbey, hoping to be Skipper of otters like her father, and was close friends with Tribsy, Girry, and Brinty. She was incredibly skilled with a sling, calling the one she carried "Wuppit". On one trek into Mossflower Woods, the foursome encountered Groffgut's gang torturing Pandion Piketalon. Tiria, an expert slinger, rescued the bird and acquired an iron barb that was stuck in his mouth from a battle with Riggu Felis.That night, Tiria dreamed of Martin the Warrior and the original Rhulain, who instructed her to liberate the otterclans of Green Isle. After she remembered the dream, Brantalis Skyfurrow gave her directions to Salamandastron. Following another vision from Martin, Tiria, her father, Pandion, and Brink Greyspoke immediately departed for Salamandastron.
Captain Cuthbert Blanedale Frunk, Log-a-Log Urfa, and the Guosim assisted in transportation via the Purloined Petunia to the mountain, where Lord Mandoral Highpeak outfitted her with the original Rhulain's armor, crafted by Lord Urthwyte the Mighty. Tiria was also given a new sling by Lord Mandoral.
After the Petunia arrived at Green Isle, Brantalis flew from Redwall to deliver the coronet that accompanied the armor. Tiria slung the iron barb originally retrieved from Pandion from a great distance to kill Felis. After the defeat of the Feral Cat Army of Green Isle, Tiria became queen, ruling from the halcyon Holt Summerdell. Her new companions became Deedero Galedeep and Banya Streamdog.
- Tiria was one of the few main characters who directly killed a main villain.