BACKGROUND: Peer support programmes use individuals with specific experiences to improve engagement and outcomes among new clients. However, the skills and techniques used to achieve this engagement have not been mapped. This potentially restricts the development and replication of successful peer advocate models of care. This study explored how a group of peer advocates with experience of homelessness, alcohol and drug misuse made and sustained relationships with their client group. For the purposes of this project, the client group were located among a hepatitis C-positive cohort of people who have a history of injecting drug use and homelessness. METHODS: Five self-selecting advocates gave a narrative interview lasting 40-90 min. These interviews were double transcribed using both thematic analysis and narrative analysis in order to triangulate the data and provide a robust set of findings about the unique skills of peer advocates in creating and sustaining relationships with clients from hard-to-reach populations. RESULTS: Peer advocates build rapport with clients through disclosing personal details about their lives. While this runs counter to assumptions about the need to maintain distance in client-patient relationships, the therapeutic benefits appear to outweigh the potential costs of this engagement. CONCLUSION: We conclude the therapeutic benefits of self-disclosure between peer advocates and their clients offer a moral grounding for self-disclosure as a means of building relationships with key hard-to-reach populations.