Thorn is a girl (originally named Kia) who was cursed as a young girl by an evil wizard. Kia/Thorn was transformed into a snow leopard by day, and a girl by the light of the full moon. She prefers to walk around on all fours, and can't resist the temptation of elk meat.
Samantha found Kia/Thorn when she was still little. Her paws was caught in a thorn bush, which got her the name.