A Unified Approach for Reconciling Characters and Story in the Realm of Agency

In the last decade, a number of computational systems for entertainment and communication have appeared, that share a set of common features, including the use of artificial characters and the reference to drama and storytelling. Systems for interactive storytelling and drama rely on agent theories to model characters, and adopt planning techniques to cope with non-determinism at the story level, combining them according to sophisticate architectural designs. However, a consolidated approach has not emerged yet, that fully reconciles these two dimensions. In this paper, we propose a unifying framework to accommodate the tension between story control and character behavior and we claim that the accurate modeling of agency is a prerequisite to the success of attempts to solve this tension. By using this framework to analyze practical systems we point out that the importance of agency is acknowledged by successful systems, although only implicitly in most cases.