This paper outlines a view of early relational trauma as underlying borderline states of mind, and argues that Knox's 1999 paper on internal working models and the complex provides a basis for understanding such states of mind. The author argues that in addition to internal working models, the complex also embodies and contains primitive defences of the core self. He outlines how these apply on the objective, subjective, transference and archetypal levels, and in direct and reversed forms and applies this to the account of Fordham's analysis of his patient ‘K’, which ended in impasse. The paper explores the dynamic that emerged in that analysis and suggests that it could be helpfully accounted for in terms of the co-construction and reconstruction of early relational trauma in the analytic relationship.