The betweenness centrality is an indicator of network structure of particular interest to sociologists. It measures, for each of the alters in a personal network, the proportion of shortest paths between all the other alters that pass through it. This measure is strategic first of all because it links the overall structure of the network to the characteristics of its members. Second, it shows the ability of certain alters to bridge parts of the network that would otherwise be disjointed. These individuals thus establish a rare link between structurally dissociated universes. They are in a position of "passers" between different social circles. Based on a longitudinal qualitative panel survey that examined the personal networks of 87 youth along five survey waves over 20 years, a total of 306 networks were available. These networks are made up from a system of name generators based on current living contexts and past contexts from which relationships have been maintained. The most central alters in betweenness are identified by an original method. It is based on the following idea: if we simply sort the betweenness centralities of the alters in order to hierarchize them, we underestimate their interdependence, as the betweenness of an alter is partially linked to that of the preceding alter in this sorting if they are connected. Indeed, each central alter "brings" a part of his centrality to his neighbors. The hierarchy of betweennesses is thus "biased" by the position of the most central ones. We proposed a method for a progressive deconstruction of networks which, by eliminating the most central alters and recalculating the betweenness of the remaining ones, allows to measure more “local” betweennesses. We then ranked more accurately each of the alters with this recalculated betweenness. The question asked here is : Who are these alters who have such a special position? What gives them this ability to link social universes? With quantified data we identified the effects of contexts (work, leisure, etc.), social roles (family, spouse, etc.), characteristics of alters (occupation, residence, etc.), qualities of relationships (duration, multiplexity, etc.), and finally biographical transitions along the life course (marriage, divorce, migration, etc.). But in some cases, the interpretation of betweenness does not clearly fall within this broad data analysis. It is then interesting to switch to the qualitative dimension of these data. We do this by matching, for these ranks of betweenness, the ID of the alters with their first name as cited in the comprehensive interview conducted with the respondent, and by reading all the verbatim about him or her. In addition to the illustration of the "why" of the effects of context, roles, and characteristics of the alters and relationships, we can then understand, with the stories of the relationships told by the respondents, why these cases are in a position of betweenness. It is therefore by combining these two quantitative and qualitative dimensions that we make further progress in understanding the link between network structure and lived stories.