In this paper, we investigate collective agency from both normative and formal perspectives. Moving beyond prior literature that primarily emphasizes preference dependency or coalitional power, our analysis highlights the critical role of norms—encoded as ordered (conditional) imperatives—in facilitating the emergence of collective agency. Drawing insights from game theory and default logic, we propose a novel default theory to capture how norms change game scenarios. We present formal proofs establishing corresponding relationships between this default theory and strategic game models, and extend these findings to multi-game scenarios. Our technical results enhance the understanding of the interplay between norms and agency, providing an initial formalization for applying these interconnected theories.