Hi all. I put this in another thread after I came up with this realization. Oh, don't give me that look! That thread went off topic by the second page!
Anyway, the realization I had was that there is no third entrance. The inaccessable door near the GECK chamber actually leads to the Vault Door (Don't believe me? TCL your way through.) And since super mutants aren't going through Little Lamplight, that means they have to be using the main entrance.
But what about the radiation at the door? People will die going through it! YOU die after 1000 rads!
Yes. But here's the thing: the lethal dose of real-world radiation is at 600-3000 rads. But it's lethal in the same way as losing heart or your jugular getting severed: the wound is fatal, but it doesn't kill you immediately. It takes a while for the body to die from severe/acute radiation poisoning. After a dose of at least 3000 rads, death comes within 48 hours, with 100% lethality. The death at 1000 rads is a gameplay mechanic- likely signaling that your body is too weak to carry itself anywhere and will shortly become radroach food.
Anyway, the FEV chaimbers are a hop, skip, and jump away from Vault 87's main entrance. Not too far for the mutants to carry their freshly-irradiated and dying captives to get exposed. Once exposed, the FEV fixes the radiation damage as it mutates the person into a centaur or super mutant. This makes sense, as Super Mutants are immune to radiation, and presumably centaurs as well.
But FEV on anyone even slightly radioactive is always lethal!
Only in the Mariposa Strain. Remember: Vault 87 was running their own experiments on FEV. Unless the two were in communication and sharing notes, the two strains were developed differently. So it's an assumption to belive that the two strains would behave similarily.
Even then, radiation is noted to be a constant hazard in the Capital Wasteland; the only consumable items that aren't irradiated outside of chems are the hyrdoponically-grown food in Dr. Li's lab and purified water. Everything else gives at least a little radiation. This means that the Super Mutants would rarely have been seen in the capitol wasteland, because as soon as they got out of Vault 87... nobody they brought back would become like them.
But what about the Enclave? The used the same way to get in!
They also have drugs that protect them from lethal levels of radiation, as seen when James sabotauges the purifier. The only reason Autumn collapsed was likely because he hadn't given himself the drugs before getting exposed; he had recived a lethal dose immediately, and used the last of his strength to inject himself with whatever super Rad-X/Radaway the Enclave gives so he could survive.
It's not a stretch to think that they knew the area was irradiated beforehand, and dosed themselves before hitting the entrance. They then give the LW the same drugs to bring him/her back out.
So what Happens?
Here's what I think; they drag their captives through Vault 87's front doors. The high radiation immediately puts them at the brink of death. The super mutants, who are used to their captives going limp when they approach the door, don't discard anyone. The captives are brought to the FEV chambers and gassed. After the gassing, they're then brought to the isolation chambers (the ones near Fawkes) to recover. They throw several people into an isolation chamber, and this is important.
Explorers would remember that the chambers have one of three things: multiple "fresh" dead bodies, a centaur, or an insane survivor.
The dead bodies are those who succumbed to radiation poisoning before the FEV could affect them. The super mutants toss 'em into an isolation chamber because they can't really tell the difference between a dead person and a person who is dying from severe radiation sickness- both are limp, and don't move or speak much after passing through the entrance. They probably don't clear out the chamber until the bodies begin to rot- a clear sign that the FEV procedure didn't take hold.
Centaurs might be what happens when you have multiple survivors infected with FEV in constant close contact (since, at most, only skeletal remains are found in their rooms.) Or they ate the dead bodies of those who didn't survive the process, either one is valid.
The insane survivor, having survived the radiation and FEV long enough to get back on his feet, is actually becoming a Super Mutant. As the V87 research on FEV notes, it takes several days for the FEV to reach the end stage; the insane guy is still in the early process of being changed, he might have "arrived" a few hours or a day prior to the Lone Wanderer's raid on Vault 87.
As one person put it: It's like a Super Mutant event horizon. Once the mutants bring you through the front door, you're coming out a mutant... or not at all.
Thoughts?