Taking the recent relational turn in the discussion on care as a point of departure this contribution aims to ask: What are ways of a critical artistic practice that take care seriously as a challenge to the theatre apparatus, its aesthetic, its dramaturgy and to the way it thinks-with bodies, objects, materiality and more-than-human ways of existence? In which ways can performance find other modes of representation for that which matters within the theatrical frame but that usually exceeds its paradigm of visibility? By focusing on the performance Living Matters (2019) by German artist Eva Meyer-Keller, the article explores relational ways of thinking-with in the apparatus of theatre while interrogating its scopic regime for its exclusions and blind spots. In the performance, where grapes mutate into fluorescent deep-sea monsters under the eye of the microscope and where tampons perform cell division, scientific processes are interrogated rigorously as to their normative structures and presuppositions – but in such a way that consistently takes into account the theatrical peepshow apparatus in which the work unfolds. The article argues for a dramaturgy of response-ability which problematizes the purportedly ‘neutral’ frame of the black box, its objectifying gaze and the way it constructs objects and viewing subjects. Relationality is thereby understood not as a mere thought experiment, but as a theatrical practice of response-ability towards, with and by (more-than-human) accomplices.