When traits meet contexts: how interpersonal relationships shape the association between dark tetrad traits and cyberbullying bystander behaviors

Introduction Bystander behaviors can influence the consequences of cyberbullying incidents, yet little is known about how dark personality traits could affect this behavior when strangers or friends are involved. This study examined whether contextual moral disengagement and state empathy mediated the associations between dark personality traits and cyberbullying bystander behaviors, and whether these pathways varied across bystander relationships with the perpetrator and victim. Method Chinese emerging adults aged 18–25 years ( N = 451; 43.0% male, 56.1% female, and 0.9% preferred not to report gender) were recruited from Weibo and completed a 2 (perpetrator: friend vs. stranger) × 2 (victim: friend vs. stranger) between-subjects online experiment. Results Machiavellianism, hypersensitive narcissism, psychopathy, and sadism were associated with more passive and negative bystander behaviors and fewer positive bystander behaviors, whereas communal narcissism showed the opposite pattern. Path analyses showed that contextual moral disengagement mediated associations of hypersensitive narcissism, psychopathy, and sadism with bystander behaviors. State empathy mediated relationship of psychopathy and communal narcissism with passive and positive bystander behaviors. Interpersonal relationships did not moderate the links between dark personality traits and the mediators, but moderated specific direct associations: perpetrator relationship moderated the effects of psychopathy and sadism on passive bystander behavior, and victim relationship moderated the effect of hypersensitive narcissism and communal narcissism on positive bystander behavior. Conclusion These findings highlight the cognitive, emotional, and interpersonal mechanisms linking dark personality traits to cyberbullying bystander responses. Prevention and intervention programs may benefit from addressing moral disengagement and strengthening empathy to reduce passive and negative bystander behaviors and promote positive support. The findings also suggest that intervention efforts may need to consider the interpersonal context of cyberbullying, particularly whether the perpetrator or victim is a friend or stranger.