While much research has been devoted to understanding how peer tutoring benefits tutors, less attention has been given to how peer tutors develop pedagogical content knowledge as an additional benefit of working with students as they write. In this qualitative study of 15 undergraduate Writing Fellows (writing-focused peer tutors who work in large undergraduate gateway courses at the University of Michigan), we explore how Fellows describe their interactions with students in order to understand how they developed more nuanced knowledge of content and honed their pedagogical skills. We use the framework of interpretive and hermeneutic listening in a novel way in order to understand how the Fellows' listening orientation towards students informed their pedagogical strategies. We found that Writing Fellows took students seriously as sense-makers and used their numerous interactions with students and their close proximity to novice perspectives to develop flexible thinking about the subject and to inform their teaching.