This paper explores post-humanist assemblage and biomediation through ontological storytelling and antenarrative. It considers material agency via biomediation, examining the use of material devices to prolong and enhance human and animal life. The first ontological story presented is that of a woman and her biomediated dog (titanium knees), running in an urban setting with various material actants in assemblage supporting human health and psychological wellbeing. The second considers the use and efficacy of biomediation to prolong the lives of humans afflicted with renal disease and cancer. The work offers an experiential lens for contemplation of biomediation, assemblage, posthumanism and ethics. Its contribution is an authentic, contextual exploration of Heidegger’s (1962) Dasein and a related antenarrative fore-having of metanoia-derived strength. These illustrations support discussion of how material (ontic) and ontological (Being-there) aspects are overlooked or actively suppressed by social constructionism.