Epilepsy is a chronic condition that significantly affects the lives of individuals with epilepsy and their support persons, though few studies have examined the experiences of both individuals. To examine these experiences and explore the interpersonal relationships between dyad members, we conducted in-depth interviews with 22 people with epilepsy and 16 support persons. Data analysis was guided by a grounded theory perspective. We developed a model that shows how epilepsy impacts the lives of both people with epilepsy and support persons and how the experiences of people with epilepsy and supporters influence one another. The core model elements were seizure and treatment factors, relationship characteristics, self-management, seizure control, support provided, illness intrusiveness, and quality of life. People with epilepsy moved through the model in five trajectories depending on seizure control, relationship type, and gender. Support providers followed four trajectories based on seizure control, perception of burden, and support for themselves. People with epilepsy and their primary support providers have varied experiences in how epilepsy affects their lives. This model could serve as a basis for future research and intervention efforts focused on ways to reduce illness intrusiveness and improve quality of life for people with epilepsy and their supporters.