This article explores Korean English teacher’s co-teaching practices and perspectives through a narrative inquiry of a high school teacher, Ms. Lee. It examines her lived experiences and perceptions as she goes through her first journey of co-teaching in her eleven-year teaching career. Data for this study consist of 12 reflective journals, two face-to-face interviews, and three follow-up email interviews. Ms. Lee’s stories illuminate a journey in which she developed a deeper understanding of co-teaching and co-teachers’ roles. Throughout her journey, Ms. Lee maintained her initial view of her primary role as an aide, but co-teaching experiences offered her opportunities to consider her position from various perspectives and thus construct her identity taking multiple roles. Thus, within the anchor role of a helper, she performed various roles for the students, such as a class management aide, a careful mediator, and a psychological supporter. She also served a couple of roles for the native English-speaking teacher (NEST), such as an instruction partner, a crisis manager, and a secretary. In her narratives, Ms. Lee also shared her view of the NEST’s roles and suggested ideas for better co-teaching. Based on the analysis of her narratives, this article highlights practical implications for co-teaching.