The story of a lifetime is far from trivial for those who listen to it attentively. Because what an individual says about his or her life can potentially echo in the personal history of the listener, especially when the listener shares more or less similar living conditions with him. This is why the recipient sometimes sees part of the film of their own life in what is told. Expressed during interventions based on a narrative approach in a group context, this biographical resonance of the individual story deserves rigorous analysis because it is accompanied by major issues on the epistemological, methodological and ethical levels. This article aims to report on how the experiences of each challenge the other participants in the development of their individual narrative and the clarification of their conditions of existence. The materials analyzed were collected as part of a research-intervention project, “From life history to life project”, carried out between 2015 and 2018 with groups of young people of both sexes (from 17 to 28 years old) from disadvantaged neighborhoods in Port-au-Prince. The subject is a continuation of a reflection proposed by Jean Leahey (2011) in the field of psychotherapy and falls within the theoretical environment of biographical research.