Drawing from a study of one student's literate engagements with English studies and fan fiction and related fan art over her two years in an MA program, which also reached back to the earlier writing she did for English classes and other writings before the study began, this article employs sociohistoric theory to examine the profoundly dialogic interplay of vernacular and disciplinary literate activities. Following a detailed look at the student's extensive involvement with fan fiction, the article elaborates the trajectory of linkages between fan fiction and English studies, paying particular attention to the repurposing of literate practices across these activities, the synergies and tensions that texture such interactions, and the long-term implications they have for the production of literate practice and person. Ultimately, the article argues for increased theoretical, methodological, and pedagogical attention to the heterogeneous assemblage of literate practices and identities that may be mediating literate action and, in particular, to the role vernacular literacies can play in developing disciplinary engagement and vice versa. (Contains 1 table, 2 figures, and 4 notes.)