Born Wheeling Gull Isle, in Undersea. After living there for a year, she and the majority of Undersea left, to live with family on the mainland. Nearing two years of age, she returned to Wheeling Gull Island, but found no one she recognized so she journeyed further inland to return to her family.

On her way, she would meet a trio of brothers travelling together- Skipper, Scallion and Pike. The twins- Skipper and Scallion- while harmless, were incorrigible jokesters and made fun of her for being shy, but were told off by Pike, who was gentler, kinder. By the time they found a valley to claim she and Pike had become mates, and she brought three daughters into the world late that summer.

For another year they lived in the valley but due to the unsettling presence of a pack nearby that had begun to push their boundaries, tensions built up. Not long after giving birth to two more daughters in her third year, the pack started getting harassed more regularly, especially when a nomadic pack had come to settle in an alliance with their rivals. When winter came, a famine arrived- and Thresher and her family were forced to leave their valley. They began to rove West, toward the lands she had once called home, making a hard journey through the winter months.

While travelling along a ridge in the mountains, the pack was separated by an avalanche. Thresher ended up stranded on the North side of the mountains alone, while the others were forced to the South. Unable to breach the mountain at that point after the avalanche, they called to one another, promising to follow the mountain range West, where they might meet again at the seashore. She passed near the Teekon Wilds once, roving along the shore, eventually roving inland and continuing her search for a year. Over time, her journeying has brought her back to the Wilds, in hopes her family might find her there.