Seven Kingdoms: Seowyn's Crossing
Tween is a shifter girl of about ten. She and her twin brother Twixt were found by Ghost in the Faewyld where they were living as street thieves along with an older shifter boy named Fish who looked after them. Tween is the more outgoing of the twins. She’s level-headed and practical, and tries to think things through. She’s also very clever and is very protective of Twixt.
Twixt and Tween are too young to remember anything of their tribe, being orphaned with no memories of even their parents. They are now living, along with Fish, with Ghost’s elven mentors/foster-family Arun, Jariel and Vondyr where they are being trained in the same ways she was.