"It/I" is a two-character theater play where the human character "I" is taunted and played by an autonomous computer-graphics character "It". We believe that "It/I" is the first play ever produced involving a character reactively controlled by a computer. Autonomous characters can bring a new dimension to the theater experience by enabling the audience to go up on stage after the performance and interact directly with the characters, re-enacting the story of the play. This paper reports the experience and examines technical developments needed for the successful production of "It/I". In particular we describe the interval script paradigm used to program the CG-character, the proposed SCD-architecture for story-based interactive systems, and the ActScript language for communication of actions and goals.