....well, lets see.... Why would FEV be in a Vault...maybe because the military seized it and could place it wherever they wanted? I mean, the military seized the ZAX and placed one in West-Tek, so why wouldn't it place West-Tek developments in Vault-Tec facilities? Considering the Enclave were preparing for nuclear war, placing an FEV testing facility underground at the same time as bringing FEV testing to the newly finished Mariposa Base makes sense. Also, FEV also existed at West-Tek meaning that it all wasn't brought to Mariposa Base and could also have been brought elsewhere. Maybe there's several unkown FEV facilities underground in Military bunkers as well? There's plenty of military prisoners afterall and research is better done en masse. Through a Vault, the Enclave could see how well the virus works on drafted citizens without military training. Through military prisoners, they could see how they could use China's own men against them. Also, is it ever mentioned that the FEV in West Tek that resulted in the Master was the same as the Mariposa Base FEV? Different research directions could have occured, one focusing on phsyical evolutions and the other mental. FEV in Mariposa Base is also a much MUCH less developed product than that used in the EEP. I don't see any mention on when the EEP occured, it could have been years after the vault closed, meaning the virus could have been tampered with for 100+ years before it became what we see in Fallout 3. This is also why the androids can happen too: The Institute has been conducting robot improvements and research since the bombs dropped. 200 years more time for further development. And why CAN'T FEV result in extremely huge super mutants? I mean, extremely huge rats, ants, scorpions, and geckos can exist, but not tripled sized humans? Huh? Sides, the virus in Fallout 3 seems to build on itself over time, sort of like a tree growing I guess. The Super mutants get bigger, and bigger, and bigger until their bodies can't support themselves over time. Look at the failed tests: Part of their body grew too fast for their body to handle. The dim wittedness was common in Fallout 1 too, seeing as how only a few actually have intelligent conversations with you...the rest just stand around with guns, attacking when they are told to. If anything, the FEV in Fallout 3 is probably what the military was after. Look at Psycho! It's engineered for killing, not thinking So yeah, it could exist in Vault 87 without plotholes. The only contradiction I see is that the Vaults in Fallout 3 were all started when logs say that all Vaults should be finished, except Vault 13.