This study introduces a two-dimensional variable damping controller for implementation in wearable robots. The controller applies a range of robotic damping between negative and positive to the coupled human-robot system. A wearable ankle robot was used to test this controller, and human experiments were performed to understand and quantify the effects of the controller. Subjects performed a target reaching exercise while the robot provided constant positive, constant negative, or variable damping. These three damping conditions could then be compared to analyze the performance of the system in terms of stability, agility, and effort.