Walden was a hybrid, having the lower body of a shark, and the upper body of a human. He was violent to his captors and caretakers, hating the lack of freedom. He stayed in a large, long tank filled with water and fake sea grass at the bottom. He hated how people would look at him like a freak, treating him like one too. Anytime someone got to close to the water on the top, he would pull them under and drown them.