 Olivia and Peter learn Greg was being treated for a sleep disorder , and that his dreams had involved demons until they stopped several months ago . Another hallucinating victim turns up in Seattle and dies . The Fringe team discover that both victims had a brain – computer interface chip attached to their thalamus , the part of the brain controlling dreams . Broyles ( Lance Reddick ) and Nina ( Blair Brown ) reveal new information leading to the sleep researcher Dr. Nayak ( Ravi Kapoor ) who implanted the chips . Another victim named Diana ( <unk> Huguet ) hallucinates at a restaurant and kills a coworker before similarly dying of exhaustion . 
