Foreign or second-language (L2) pre-service teachers (PSTs) are simultaneously learners and teachers of the target language, adding to the complexity of teacher education. How these two identities are intertwined with their pedagogical beliefs and dominant ideologies has not been fully investigated, especially with PSTs in longitudinal studies. To fill this gap, this 15-month critical ethnography followed Ariel, a Chinese PST of English, as she transitioned from learner to teacher in an undergraduate teacher education programme. Drawing on a model of L2 investment and data collected from interviews, classroom observations, participant artefacts, diaries, and narratives, this study demonstrates how Ariel started the journey with a strong motivation to learn and teach English but did not remain invested in her teacher identity and divested from certain English learning and teaching practices that index ideological conflicts. Pedagogical implications are provided for PSTs to be empowered by opportunities that accentuate their beliefs and voices.