The aim of this study was to investigate student teachers' agency in their identity negotiations as first-year students on a path towards becoming teachers. A narrative inquiry approach was employed in the analysis of the interviews conducted with 16 Finnish student teachers. One master narrative and two counter-narratives were identified in which student teachers' agency was manifested in teacher identity negotiations. The master narrative suggested sustaining internalised preconceptions of teaching. The counter-narrative of transforming teacher identity illuminated a transformation from preconceptions towards a teacher education's institutional, culturally bounded story of teaching. The counter-narrative of questioning teacher identity entailed questioning the normative master narratives of teaching and actively producing counter-narratives. The findings highlight the importance of recognising and unravelling the master and counter-narratives in teacher education, which may guide the nature and varieties of teacher identities and agency possible for future teachers.