Unfinished Legacies turned the platforms where teen culture and trust live into a fentanyl overdose prevention tool. With families’ permission, we used AI to recreate the voice and likeness of victims so they could deliver their final words through their own social accounts, for proximity, not spectacle. By using the victims’ identities and networks as the channel, the warning reached friends and peers as something familiar, personal, and impossible to dismiss. It earned 15.1M impressions in a metro of just 2M and Kansas City saw a 34% reduction in overdose deaths after the campaign period.