Most agree that personas are built on data, but several have experimented with purely fiction-based personas. These personas are often used to explore design and generate discussion and insights in the field. There are several suggestions to use fiction, here are a couple of links for inspiration:
Ad hoc personas are based on the designers intuition and experience and used to create an empathetic focus in the design process.
Assumption-based personas capture the organization’s current thinking about the customers.
Extreme Characters help generating design insights and explore edges of the design space.
Pastiche scenarios creates personas derived from fiction like Bridget Jones or Ebenezer Scrooge and help designers to be reflexive when creating scenarios.
Proto-personas originate from brainstorming workshops where company participants try to encapsulate the organization’s beliefs (based on their domain expertise and gut feeling) about who is using their product or service and what is motivating them to do so. They give an organization a starting point from which to begin evaluating their products and to create some early design hypotheses.
Discussions about validity and value have emerged (e.g. When does a Persona stop being a Persona and Assumption personas help overcome hurdles), and the article Beyond Fake Personas suggests a continuum from Persona Sketch, over Persona Hypothesis and Provisional Personas to Robust Personas ending in Complete Personas.
Most important is to remember that fiction based personas are for discussions and explorations rather than actual design.