Interactive Drama applications aim at offering interactive experiences to the participants by empowering them with active participation and engagement in the development and solution of a story. However, introducing this interactivity leads to a natural conflict between the participant's freedom of interaction and the system's control, or, more precisely, the author's expectations in the development of the story. As such, favouring one over the other, leads to different experiences and perhaps even different genres. This balance has been extensively discussed amongst researchers in the community, and yet achieving such balance is still regarded not only as a challenge but also as an art itself. In this paper we discuss a system, I-Shadows that is an Interactive Drama based on Autonomous Affective Characters and Drama theory. In this system we tried to reach such balance through considering the storytelling experience as the collaboration that emerges from the real actors (the users) and the virtual actors (some Chinese shadow puppets). Supported by improvisation theory, our actors (shadows) act as if they are collaborating with the user in achieving the story. However, to achieve that, the virtual actors need to have an agent architecture that supports emotion reactions, goal oriented behaviour and social interactions. Aspects such as role taking, waiting for the right time to say their line, have a coherent personality, turn taking, and others, are considered in the minds of the virtual actors, allowing for this balance to be reached. Furthermore, and to complement this aspect of autonomy of the agents, the coordination problem between the actors is also helped by the presence of a specific agent (a story director) that allows for agents to appear or disappear from the scene of the story. This approach was used in the construction of I-shadows, which, although not yet evaluated, has revealed its power.