Background <p>Adolescent depression accompanied by non-suicidal self-injury (NSSI) is commonly recognized, addressed, and continuously reshaped within the family context. Existing studies predominantly focus on risk factors or caregiver burden, with limited attention to how family members jointly construct and renegotiate meanings of illness, self-injury, and safety over time. This study aimed to explore the interactional experiences of adolescents with depression and NSSI and their primary caregivers across illness stages, and to examine how psychological meanings and relational regulation processes are co-constructed within the family system.</p> Methods <p>A longitudinal dyadic interpretative phenomenological analysis was conducted. Ten adolescent-caregiver dyads (<i>N</i> = 20) were interviewed during hospitalization (T1) and at 1 month (T2), 3 months (T3), and 6 months (T4) post-discharge, with optional joint interviews at T3–T4. Analyses followed an idiographic-to-dyadic and cross-temporal trajectory approach, attending to psychological convergence, divergence, and critical turning points across time.</p> Results <p>A temporal trajectory of family meaning co-construction was identified. During hospitalization (T1), family interactions were often reorganized around risk containment, with NSSI-related distress commonly treated by caregivers as requiring immediate safety-oriented responses. In the post-discharge middle phase (T2–T3), some families entered a seemingly “quiet period,” which emerged as a key divergence point in dyadic adjustment. For some, reduced overt conflict functioned as a buffer that enabled tentative relational adjustments; for others, the same quietness was experienced as heightened uncertainty, which could intensify vigilance and avoidance and maintain less workable interactional cycles. By the later follow-up (T3–T4), several families negotiated lower-intensity yet sustainable interactional patterns through waiting, reduced reactivity, and shared safety cues, which, in some families, appeared to support a form of limited stability and more workable distress co-regulation.</p> Conclusions <p>Family experiences of adolescent depression with NSSI may be understood as a dynamic process of relational meaning-making and psychological adaptation. These findings should be read as interpretive and context-bound. They tentatively suggest that clinical work may benefit from attending not only to safety management, including suicide-risk assessment where clinically indicated, but also to how family members renegotiate boundaries, signals, and responses under ongoing uncertainty.</p>