Contributing to a scientific field is not always a scenic route. One cannot always act in the world according to the posted signs others have thought constituted relevant information. In doing so, one would prevent itself from taking uncharted roads with possibly much to discover. This autoethnographic journey of a didactician of mathematics tells the story of what might happen if we take a side road. Moving from a deficit-oriented perspective of professional development, summarized as teaching didactic knowledge to teachers, to contributing to the development of the teachers’ didactic thinking as a tool for agency is not easy. To do so, one needs to become conscious he needs to listen to the other, really listen, which can be risky. I needed to listen to what Ms. Callaghan had to say and she needed to listen to what Javier, her student, had to say, even if it did not fit our respective intended narratives. This is the story of how a didactician and a teacher worked together to raise each other’s consciousness and bring forth a new orientation for the development of a didactic of mathematics that anchors itself in and for actual people teaching–learning mathematics.