This narrative inquiry, grounded in Vygotsky's theory of the social situation as a source of development, explores the trajectory of a Business English teacher1, Siqi, by examining her experiences ("perezhivaniya") as both an L2 learner and a professional, focusing on shifts in her identity over time. Using "perezhivanie" as the unit of analysis, which integrates both affective and cognitive and personal and social dimensions, the study illustrates how she engaged with the "'ideal form'" within her social environment and adapted her "'real form,'" shaping her development and identity. The study also reflects on the theoretical and methodological applications of these concepts. It offers practical suggestions for institutional design to support teacher development and raise teachers' awareness of their social environment as a source of development.