Most schools operate as hierarchical structures, where adult stakeholders largely dictate what counts as knowledge and how to teach it. While previous scholarship has documented the promise of youth-led initiatives to trouble hierarchical structures, these explorations tend to occur outside of schools and do not typically account for the kinds of changes in relations between youth and adults necessary to disrupt hierarchical structures from within. Using third-generation cultural-historical activity theory as our theoretical framework, in this study we explore the shifts in subject-subject relations that emerged as high school youth literacy mentors, their teacher, and university researchers participated in iterative processes of co-configuration to open up new possibilities for literacy learning at their public school. We examine how youth mentors and adults co-designed and co-taught the Literacy Mentorship Class (LMC) while increasingly engaging contradictions as double binds within the Literacy Mentorship Debrief (LMD). We trace how evolving subject-subject relations in the LMD contributed to shifts in divisions of labor, rules, objects, and mediating artifacts in and beyond the LMC. Ultimately, we propose debriefs as a set of reflective practices to facilitate future possibilities for co-configuration among youth and adults that can be responsive to the particularities of any school community.