The author reflects on the function of working in pairs as the smallest formalizable dimension of institutional work in psychiatry, in the sense of working together with others, in the context of a day hospital for psychotic adults. This is another way of envisaging, transversally, the incarnation of a first real institutional third party. The author begins by explaining some of the organizational arrangements such as the double nursing and medical reference or the rule that there should be “at least two” people running a therapeutic workshop. She then introduces a clinical vignette illustrating the slow emergence of an appropriation of the body and of psychical intimacy through the relations between the daily care provided by the referent nurse, consultations involving three people, and therapeutic workshops as a matrix of the transference. However, beyond the organization based on working in pairs, the author also emphasizes its uncertain dimension as a space of openness that is always potentially emerging.