Had been doing the Railroad's bidding, but decided to enter the Institute and align myself with them to see what happened. Told Father I was 100 % behind him. No doubts at all. Did some quests for him. Then he sent me to Bunker Hill to retrieve 4 gen 3 synths that did not want to come home. Don't remember the name of the quest, but I was to meet a courser there and get the synths back. Met the courser and there was already a huge battle in full swing. Railroad soldiers fighting synths, Brotherhood fighting Railroad, and synths fighting everyone, I wasn't sure who to shoot at first. Prior to entering the Institute, I had done work for all the factions and not burned any bridges yet.
So I started to shoot at both BOS and Railroad just to see what would happen, and none of them shot back at me. They all just continued to fight among themselves while I killed them all. No one fired a shot at me! And weirdest of all was how my companion Piper reacted. She followed me around through the whole ordeal with her gun drawn. but never fired a shot at anyone. She was probably thinking to herself, WTF is he doing shooting all his old friends. Very strange. But I found the 4 gen 3 synth's in the basemant, deactivated them with the code and finished the quest.
Just thought I would pass on this bit of weirdness to see if anyone else had seen the same thing.