Using Structural Analysis of Social Behaviour (SASB), the communicative means by which a patient succeeds in re-enacting his or her own maladaptive relationship patterns in the interaction with the therapist is examined. This line of investigation stems from the work of Henry and co-workers, who have shown that therapists often unknowingly allow themselves to be drawn into subtly hostile interactions with patients, and that such interactions are associated with a negative outcome. In a mixed quantitative-qualitative single case study, the relationship narratives of a female patient from two therapy sessions are analysed using a cluster-analytic procedure in order to identify her repetitive relationship patterns. Then, using a short sequence of interaction, it is demonstrated how a central maladaptive pattern is re-enacted in the therapeutic interaction and gradually takes hold. These results are interpreted as evidence that patient communication contains paradoxical demands which can lead therapists to become part of the maladaptive pattern of interaction.