Error correction has been one of the central themes in accounting for potential gains in second language (L2) writing. While a wide range of empirical studies focused on the effects of written corrective feedback (WCF) on learners' writing outcomes, few of them have specifically examined the feedback process, or its potential role as a shaping force in learner development. Underpinned by a sociocultural framework of L2 acquisition, the present study examines learner development as mutually mediated by teacher feedback and learner response during dyadic sessions of error correction. The socioculturally informed approach, dynamic corrective feedback (DCF), operates via dialogic, collaborative negotiation over errors between an expert and a novice, in which feedback is scaffolded and tailored toward learner competence. Data collected from three Chinese EFL learners' written texts and writing tutorial sessions show that learner idiosyncrasies are evident in development trajectory, and that development is not always linear but recursive. It is suggested that teachers attend to individual needs and abilities when providing feedback so as to facilitate sustainable development.