This chapter opens with Jane’s story to establish the book’s central claim: pain precedes both diagnosis and drug use. It reframes heroin, alcohol, and other forms of self-medication as survival strategies that co-emerge with mental distress, rather than as separate, competing disorders. Drawing on critical realism, I argue that pain is an ontological ground, real, layered, and causally powerful, shaping agency and trajectories before services ever appear. Phenomenology centres how this pain is lived through the body; Archer’s morphogenesis explains how people improvise within constraint. The chapter sets the ethical stakes: systems fail not because people are unreachable, but because pain is unreadable within diagnostic grammars. We begin, therefore, not with compliance or abstinence, but with recognition of pain as signal, meaning, and ground zero.