DiMA DiMA is a modified synth on the Island in 2287 . He is the founder and leader of Acadia . Background . DiMA , alongside Nick Valentine , is one of two early prototypes created by the Institute to test if synths could handle independent thinking and judgement . While DiMA was allowed to freely develop his own personality through experience , Nick was outfitted with alternating , pre - existing human personalities . The two formed a close sibling relationship while in the Institute together , in DiMA ' s words : " I literally saw myself in you " . DiMA , not being able to bear seeing his brother put through such cruel experiments , decided to run away with Nick and the duo eventually managed to escape . However , disoriented by the experiments done to him , Nick did not recognize DiMA after escaping . Believing himself to be the human Nick Valentine , Nick attacked DiMA , forcing DiMA to knock him out and then abandon him . Afterwards , DiMA traveled to Far Harbor to hide from the Institute , though without a programmed objective . He sat in a cave doing nothing for nearly a year before it occurred to him that he could define his own path in life . He then went on to live in an old nuclear - armed submarine base that was eventually discovered by the Children of Atom . DiMA befriended their leader , Confessor Martin , and eventually gave them the base as their home . Alongside Faraday , a synth scientist that acts as his assistant , and Chase , an ex - courser that DiMA was able to convince to defect from the Institute , DiMA went on to found Acadia with the intention of creating a safe place for synths to live freely and not have to hide their nature . From there , DiMA was able to develop fog condenser s to protect the residents of Far Harbor from the Fog , which consequently angered the Children , as the Fog is sacred to them . With tensions high between the Children , Acadia , and Far Harbor , DiMA , desperate for peace and safety for his own people , created contingency plans in the event that either group endangered Acadia . For the Children , it was acquiring the key to the nuclear missile in the Nucleus , and for Far Harbor , it was acquiring the shut down codes for the town ' s wind farm and only power source . Then , in his desperation , DiMA chose to kill Captain Avery and secretly replace her with a synth as to have a " moderate voice " to be an example of how synths and humans could live side by side . DiMA was so sickened by his own actions that he chose to remove these memories and , as a sign of good faith , put them in the Nucleus ' computers for the Children to safeguard . Sometime later , DiMA and Nick are reunited when Nick and the Sole Survivor travel to Far Harbor looking for Kasumi Nakano . While DiMA expresses surprise and excitement to see Nick again , Nick is far more reluctant , not having any memories of DiMA due to their last encounter being over a hundred years prior - - memories DiMA has been able to maintain through his many modifications . However , if the Sole Survivor encourages Nick to accept DiMA as his brother after finding the holotape of their fight , Nick will apologize to DiMA and the two will occasionally greet each other or chat when entering Acadia . Interactions with the player character . Effects of player ' s actions . Based on the player character ' s actions , DiMA can become an ally or an enemy . Appearances . DiMA appears only in the " Fallout 4 " add - on " Far Harbor " .