Role-Playing Prompts: Building Personas That Hold Up Under Pressure
Role-playing personas collapse without specific expertise, voice, and boundaries. Here is how I build personas that hold up. Role-playing prompts assign the model a persona, and they are powerful exactly when they are specific and dangerous when they are vague. A specific persona produces consistent voice, scoped knowledge, and behavior that fits the role. A vague persona produces a model that drifts between voices, claims expertise it does not have, and breaks character when pressed. After building persona-driven features for support, tutoring, and simulation, I have a structure for role-playing prompts that produces personas that hold up. This guide covers that structure. The Persona Anatomy A role-playing prompt is more than a role line. I build personas from five parts: identity, expertise, voice, boundaries, and behavior under pressure. Identity names who the persona is. Expertise defines what they know and what they do not. Voice defines how they speak. Boundaries define what they refuse. Behavior under pressure defines what they do when the user pushes against the boundaries. Most role prompts include only identity, which is why most personas collapse under real use. Identity names the persona and their background. Expertise scopes what they can speak on with authority. Voice defines their speaking style and register. Boundaries define what they will not do. Pressure behavior defines how they handle being pushed. Writing Specific Expertise, Not a Job Title A persona defined as a doctor is too broad to be useful.