Given that intervention has been relatively under-researched in pragmatics, this paper offers a linguistic-pragmatic examination of a case of bystander intervention, a notion which is generally known in social psychology. This study approaches the phenomenon of bystander intervention by analyzing discourse data transcribed from a video posted online. Drawing on participation status and relational identity theory, this paper investigates the issues of relational identity and relationships involved in an intervening interaction. The findings indicate that the intervener's relational identity is in a constant process of construction and negotiation, and the study also notices that three most prominent strategies in our case are employed that give rise to the effective intervention, namely humor, empathy and imposition of power, which might provide some insights into further research in this field.