Adolescence is characterized by an instability and a vulnerability of the systems of psychical functioning, within which the drive is oriented towards diverse and potentially changing outcomes. This problematic is actualized in sessions of psychotherapy, affecting their course. In addition, putting narcissism back into play in therapeutic dialogues leads to other parameters, in particular one that I have called « the transitionalization of exchanges », to which I refer in relation to the body. Drive is studied on a theoretical plane, and its place is analyzed in different systems of psychical functioning that one might find in the session. Their swift variations can pose a problem. In this context, transforming what might appear to be an obstacle to the good progression of the treatment into a therapeutic resource seems to me a clinical and theoretical goal. This work may form a basis for reflection, which should be continued and completed in the future.