In seeking to develop a richer understanding of what I do in my Theraplay practice with children who are experiencing relational and developmental trauma (R&DT), I reflected on my embodied responses to my clinical Theraplay practice. I used a heuristic inquiry (HI) process to create a safe space for not knowing. This enabled my self-search to lead to a creative synthesis in the form of a novella, A Necessary Life(Story). The recursive/reflexive process, through the regular discipline of daily writing and alongside exposing myself to a wide range of literature, led to an explicit understanding of an ontological position that I realised I already held, but that I had never made consciously concrete. The fiction served as a mirror to help me explore and articulate part of my understanding of this worldview. This led to the foregrounding of relationality and a non-binary stance instead of a more positivist/binary approach to knowledge. From this different ontology, the fiction highlighted that maternal knowing is a specific form of tacit knowing. Its characteristic features include the cherishing of dependency/interdependence, not knowing/letting go, and faithfulness. I call this tacit maternal knowing (TMK), and present the case that embracing not knowing within TMK sets up conditions that drive emancipatory, relational and ethical practice and research. Further, I argue that by making TMK central to the practice of Theraplay, and using it intentionally, the model becomes suitable to address relational and developmental trauma without further adaptation. My research process and findings are presented in fictional form for multiple reasons. It is a way of loosening my intentional bonds so I could see my resistances to TMK reflected back at me. It challenges the dominant hierarchy of binary knowledge as the highest order of knowledge. It is an ethical device to protect the identity of vulnerable clients while at the same time seeking to give voice to those clients in a way that I make no claim to be the truth or their truth. Fiction, therefore, creates an invitation for the reader to join me in a position of not knowing, and from there to respectfully express the desire to know others through a commitment to, and engrossment in, caring. The research has significant implications for my own self-understanding and understanding of the relational, ethical and emancipatory nature of my Theraplay practice. It also has implications in the training of Theraplay practitioners who want to work with children who are experiencing R&DT.