Employees who possess cross-cultural capabilities are increasingly sought after due to unparalleled numbers of cross-cultural interactions. Previous research has primarily focused on the bright side of these capabilities, including important individual and work outcomes. In contrast, the purpose of this study is to demonstrate that the cross-cultural capability of cultural intelligence (CQ) can lead to both positive and negative outcomes. Applying the general theory of confluence, we propose that expatriates high in CQ excel in customer relationship performance, while simultaneously behaving opportunistically. We also suggest that ethical relativism moderates these relationships. Using mixed methods, four separate studies generally support our predictions while also deepening our understanding of various forms of opportunism and the mechanism behind two seemingly opposing effects. Conceptual and managerial implications of CQ for opportunism, customer relationship performance, and ethics are discussed.