Through the notion of “form-of-life” Giorgio Agamben developed both a political philosophy and a modal ontology which have their fulcrum in the concepts of “immanence” and “pure potentiality”. In this context, “inoperosity” plays a central role in reconnecting quodlibetal ontology and biopolitics through the idea of a practice of immanence, namely “to inoperate” (inoprare). Considering the influence of Michel Foucault on the latter instalments of the Homo Sacer cycle, this article will discuss Agamben’s interpretation of the foucauldian works of the 80’s on ethics and subjectivity. In doing so, it will specifically take into account some minor essays and two unpublished lectures in which Agamben focuses on “care of the self” as a type of “immanence to the relationship”. What emerges from this analysis is that Agamben’s notion of form-of-life and Foucault’s notion of aesthethics of existence rely on completely different understandings of life, power and practices. Moreover, the concept of ‘potenza’/’puissance’ exposes the two different traditions of Agamben and Foucault – the nietzschean one and the aristotelian one – both interwined with immanence, but ultimately irreducible and conflicting.