This article examines the psychic function of errancy1 in an unaccompanied migrant adolescent, followed within a dispositif combining street-based clinical work and emergency shelter. Drawing on a clinical vignette, we argue that errancy operates as a form of suppléance aimed at sustaining subjective consistency in the absence of stable symbolic inscription. We conceptualize this process through two modalities: topological suppléance, understood as an attempt to construct an inner space from the outside; and heroic fiction of holding, a minimal identificatory formation that prevents subjective collapse rather than expressing grandiosity. The clinical task is to support a space of address prior to articulated demand, enabling errancy to function as a transitional operation rather than a movement toward disappearance.2.