Successful collaboration requires the integration of the individual partners’ intentions into a shared action plan, which may involve a continuous negotiation of intentions and roles. Negotiation of roles, if handled effectively, could prevent bumpy transitions of control authority between the human and robot. Lacking for Haptic Shared Control, however, is a means to identify the roles and means to monitor or measure the interaction mode between the human and a collaborative robot. This paper aims to address this oversight by employing new measures and associated analysis. Specifically, we use relative force measurement to identify the interaction mode (cooperative and non-cooperative). Furthermore, we use work as a tool to determine the roles of the human partner and collaborative robot in each of the interaction modes.