It has been shown that agreeableness of patients with borderline personality disorder (BPD) had an impact on therapy process and outcome (Hirsh, Quilty, Bagby, & McMain, 2012). The goal of our study was to test whether agreeableness affects the therapeutic alliance and outcome assessed after brief treatment for BPD, and whether this link is moderated by therapist responsiveness. We compared two types of interventions (N = 60) in 10-session treatments (Kramer et al., 2014): a general psychiatric management (GPM)-based treatment and the same treatment supplemented with motive-oriented therapeutic relationship (MOTR), based on plan analysis case conceptualizations (PA; Caspar, 1995), as operationalization of therapist responsiveness. The results showed that there was a significant link between agreeableness and outcome for the GPM, but not for the MOTR. No links between agreeableness and the therapeutic alliance were found in both conditions. MOTR enables suppression of the influences of the patient's initial characteristics on the therapeutic results.