This study examined companions' roles in interactions between patients and interdisciplinary geriatric oncology team members. Companions' roles identified include memory aid, emotional support, transcriber, aid in decision making, companionship, elaboration, advocate for patient, and interpreter. Specific patterns of variability of roles across team member disciplines include relatively passive companions who performed more active roles with physician, relatively active companions who performed more passive roles with physician, and relatively passive companions who performed more active roles when particular topics were raised, regardless of team discipline. Two patterns of stability across interactions emerged: consistently active or passive.