This paper examines the development of the concept of solidarity as expressing a sense of shared humanity, while detailing critiques of its current use, especially when it implies a privileged center setting the agenda for the sake of marginalized others. My research demonstrates how solidarity can be modified when encountering difference, and how it might be better conceptualized as "fluidarity," an attitude and practice that embraces the complexity of engaging the other in pluralized and ever-changing struggles. This engagement with otherness, an explicit part of an undergraduate theological ethics course with an embedded service-learning component, is pedagogically facilitated by a threefold reflection process required of students: critical reflection on their own narratives, reflection on the narratives encountered in their service-learning, and reflection on the lives of spiritually grounded agents of social change. Case studies of four undergraduate students demonstrate the ways in which this pedagogical strategy contributes to the development of solidarity and moves students' understanding towards fluidarity. In the end, the students gained a sense of spiritually grounded change agency, combining spiritual development with growth in critical consciousness. (Contains 1 figure.)