This case study investigates an experimental one-on-one interactive theater installation featuring a virtual AI performer built with a fine-tuned version of ChatGPT-4o. Incorporating a curated poetry database and voice cloning, the AI acted as a creative agent within a human-machine-powered dramaturgical framework, where the Dramaturge, Participant(s), and AI Agent functioned as interdependent co-creators. This triadic collaboration fostered a dynamic, flexible, and fluid creative process, notably expanding the Dramaturge’s role. The study adopts a multi-method approach, combining analysis of exhibition texts, interpretive diagrams, and holistic observation to outline the structure and operation of this co-creative system. Drawing from a personally situated, artist-in-the-loop perspective, it proposes a preliminary AI-augmented dramaturgical model, reflecting how contemporary AI technologies may reshape artistic authorship and transform creative practices.