["Health Expectations, Volume 29, Issue 4, August 2026. ", "\nABSTRACT\n\nIntroduction\nCo‐design of health services is an increasingly used method to meaningfully enable patient and public involvement, especially when working with priority populations whose perspectives are often overlooked in traditional top‐down approaches. However, differences in power and influence among stakeholders can lead to asymmetry and the marginalisation of certain voices. We used persona dyads (patient and provider) to co‐design improvements in Emergency Department care for people presenting with mental health concerns.\n\n\nMethods\nPersona dyads were used in two Experience‐Based Co‐Design workshops with patients and providers. Transcripts were analysed to understand how personas were used, when and by whom. Participants completed surveys to evaluate the persona dyads and their co‐design experience.\n\n\nResults\nPersona dyads humanised and contextualised Emergency Department experiences, fostering trust and safety by shifting attention from participants' personal histories to fictional representations without requiring personal disclosure. In the workshops, participants used the personas to establish shared understanding, enhance communication and generate creative, person‐centred solutions responsive to both sides of the care relationship. We observed differences in persona use across the workshops; there was greater reliance on the personas as participants navigated more complex patient and professional dynamics. The persona dyads facilitated empathy through not only presenting the patient but also the provider, a perspective often under‐represented in co‐design.\n\n\nConclusion\nPersonas can be a useful person‐centred, participatory tool in health service co‐design, with dyads being particularly useful for cultivating empathy, levelling power, amplifying lived experience and creating safe opportunities for priority populations to contribute meaningfully to service improvement.\n\n\nPatient or Public Contribution\nIndividuals with lived experience of mental health concerns and Emergency Department healthcare providers were actively involved in the study. People with lived experience contributed to the co‐design of the persona dyads and participated in the workshop sessions. One author, who has lived experience of mental illness, provided critical input into the design and facilitation of the workshops, with particular emphasis on creating psychologically safe spaces for participation. Two authors are Emergency Department healthcare providers and study co‐investigators. The patient and provider contributors were involved in validating the findings, and ensuring interpretations were grounded in lived and professional experience.\n\n"]