Emergency departments (EDs) often experience overcrowding, staff shortages, and long waiting times, which put a strain on clinicians and negatively impact patients' experiences. Although AI is commonly proposed to optimize clinical workflows, the perspectives of patients are often overlooked in AI design.We report on a four-phase study at a university hospital combining preparatory fieldwork, co-creation workshops, design phase, and storyboard-guided interviews. Our findings reveal a misalignment: clinicians framed the contribution of AI around triage efficiency, while patients emphasized reassurance, empathy, and guidance. Addressing both needs, we developed and evaluated a concept of an ephemeral AI companion for the ED waiting area, designed to provide orientation, support reflection, and prepare patients for consultations without substituting human contact. We contribute: empirical evidence of patients’ needs, concerns, and expectations for AI support, design principles for an ephemeral AI companion concept, and findings from a study conducted with patients during their ED waits.