This theory article develops a scope-bound structural account of how non-coercive intimate dyads may drift from integrated collaborative functioning toward adversarial surface dynamics without villainy functioning as a necessary explanatory primitive. The article treats the dyad as a coupled system operating under finite regulatory, temporal, cognitive, and affective constraints. It argues that when dyadic buffering weakens, privately carried load increases, collaborative repair loses reliability, and interpretation shifts from collaborative solvability toward audit, risk-management, and self-protection, adversarial surface dynamics may become structurally admissible without requiring assumptions of coercion, domination, or malicious intent. The paper derives a theorem-driven drift chain linking degraded dyadic integration, repair depletion, interpretive hardening, adversarial surface, negative-sum vulnerability, external salience, passive availability of alternatives, and rising exit pressure. It distinguishes this structure from coercive-control, bargaining-power, and motive-first frameworks, while explicitly excluding abuse, violence, credible-threat regimes, and coercive control from its target scope. The contribution is theoretical and structural rather than empirical, clinical, or prescriptive. It does not provide a diagnostic instrument, therapeutic guidance, or a normative account of fairness. Instead, it offers a bounded analytic grammar for describing a class of dyadic failures in which adversarial appearance may emerge downstream from degraded collaborative viability under constraint. The appendices provide pre-operational orientation material, including empirical anchor domains and a compact mapping of structural objects to adjacent literature clusters and candidate empirical signature families. These materials are intended to support future empirical operationalisation without collapsing theorem-driven derivation into measurement. DOI: 10.5281/zenodo.21214999License: CC BY 4.0
J. E. Fröderberg (Mon,) studied this question.