Once you enter Vault 87, retrieve the G.E.C.K.
Vault 87 is a ransacked vault involving tests with the FEV virus. It is filled with super mutants, who are normally equipped with Chinese Assault rifles.
The reactor level is a small area, with a few items. It's rooms have a few Rad Roaches, but also contain a few super mutants. For a quick background, there's a terminal with Peter Stevens journal, which gives a story of a technician becoming insane with the nearby children's voices.
The living quarters is still the living quarters of the vault residents, although they have since mutated into Super Mutants.
To teach the next section, head up the stairs (on the same side as the entrance from the Reactor Level), and cross the center catwalk. Head to the right, being sure to sneak past the blockade and associated room or otherwise taking care of the Super Mutants in the way.
After heading down the corridor, you will encounter Fawkes. He can assist you in retrieving the GECK as long as you help him escape the place.
- To free him, head to the right, and enter the medical wing control room.
- Pull the alarm to unlock all doors, or hack the terminal (Science 50) to unlock a single door.
- You can try hacking the terminal in front of the door (Science 75), but that doesn't help unlock the door.
If you terminate him or if he is killed en-route to the GECK, you need to retrieve it yourself. There is an Advanced Rad suit available with either Science 50 or Lockpick 75, otherwise you will have to enter the chamber by yourself.
- There is an advanced radiation suit behind a door, you may need the science skill to obtain.
- There is a very small region just before the GECK that is radiation-free. It is directly on the doorway.
Once you have the GECK, head back the way you came in order to be knocked unconscious by a cutscene and captured.