In poststructuralism, teacher agency is understood as a dynamic construct intertwined with identity, emotions, and power relations (e.g., Zembylas, 2003; Tao & Gao, 2021). Rather than an individual capacity, agency emerges through social interactions, institutional contexts, and in relationship to written genres. While research on teacher agency has primarily examined its relational aspect unidirectionally (i.e., how teachers can promote learning agency) (e.g., Maddamsetti, 2023), this chapter explores its bidirectional nature, meaning the interaction between teacher agency and learner agency, in college multilingual writing classrooms through a reflexive dialogical narrative approach. Drawing on various theoretical perspectives, we share our narratives and analyze our agency in the context of teaching writing. Our findings highlight the reciprocal nature of the agency, shaped by institutional structures, disciplinary discourses, and classroom interactions. Agency emerges through negotiations where student engagement influences instructors’ pedagogical choices and self-perceptions. We emphasize the importance of dialogic reflection, contextual awareness, and genre selection in fostering agency, enabling writing instructors to create effective writing practices in multilingual classrooms.