Trouble on the Homefront

Trouble on the Homefront is a side quest in Fallout 3 as well as an achievement/trophy.

Quick walkthrough

 * 1) Complete The Waters of Life.
 * 2) Deal with Vault 101's problems.
 * 3) Convince Amata to keep the vault closed.
 * 4) Convince the Overseer to open the Vault to the wasteland.
 * 5) Sabotage the vault's water chip and throw the vault into chaos.

Detailed walkthrough
After completing The Waters of Life, the Vault 101 distress signal can be picked up on your Pip-Boy 3000. Once you wander close enough to Vault 101, you receive the signal; Megaton is close enough. It is a message from Amata asking you to return to Vault 101 to help stop her father, the Overseer. If you killed the original Overseer while escaping from Vault 101, Allen Mack will be the new Overseer and you can still do this quest (although the radio message changes to "...the new Overseer is insane. If you can hear this, please stop looking for your dad and help save us.").

Since you and your father escaped from Vault 101, the Vault has been divided into two major factions. The faction led by Amata, holed up in your father's clinic, wants to open the Vault and interact with the outside world. The other faction is led by the Overseer and he wants to keep the vault closed permanently, in accordance with its mission. Butch however, wishes to abandon the vault entirely and live on the surface; the rest of the rebels simply intend to remain living in the vault but want to be able to make excursions into the wasteland when necessary.

One of the most essential reasons for having access to the wasteland and the remainder of humanity, apart from the obvious need for supplies and parts for the vault's aging life support apparatus, is to avoid collapse due to genetic stagnation and inbreeding. The number of Vault 101 residents has fallen significantly in the two centuries since it was sealed, implied heavily by various conversations prior to the Lone Wanderer's initial escape. If he/she successfully persuades the overseer to allow exterior access then the overseer himself will finally accept and openly admit that without external input, the vault's population will not remain genetically viable for more than a generation or so.

Although there are only three different outcomes, there are plenty of ways to finish each.

Keep the Vault closed
There are essentially two ways to keep the vault closed. One way is to ignore the problem. The downside to this is you will not receive any quest-related rewards. Another is to deal with the rebels. This completes the quest and will reward you accordingly. Dealing with the rebels can be achieved by killing them or taking an alternative diplomatic path by persuading Amata to stay in the Vault because the outside is too dangerous. There are two ways to achieve this:
 * Pass a Speech check.
 * Hack the Overseer's computer and discover the attempts by the Enclave to gain entry into Vault 101, and the Overseer's refusal to admit them. This proves the dangers outside and the Overseer has attempted to protect them and will allow you to convince Amata without the Speech check.

After dealing with the rebels, you may talk to the Overseer who will ask you to leave. If you ask him about a G.E.C.K. he will tell you that Vault 101 never had one and will offer you the modified utility jumpsuit instead, whether or not you used violence. Alternatively, you can ask him for food and ammunition and get thirteen tins of Cram and 350 5mm rounds in place of the suit.

Open the Vault
If you support the rebels pleas to see the outside world, there are several methods to do this. The most simple is to kill the Overseer; without any opposition, the rebels can come and go as they wish.

Trying nonviolent methods only work on the original Overseer; trying to reason with Overseer Allen Mack will result in him becoming aggressive. One nonviolent methods involves passing a Speech check. The Overseer will realize that the Vault won't survive more than a generation or two no matter how many supplies they may receive.

Alternatively, show that security is planning an assault against the Overseer's orders. Access the computer in the security office either by hacking into it (Average difficulty) or by obtaining the password (either from the body of Officer Wilkins or from a locker on the other side of the room). This will also allow you to free Mr. Brotch (who also knows of the plan) from the jail cell. Telling the Overseer about the assault convinces him he has failed his mission as Overseer, and he'll surrender without the speech check.

Amata will take on the role of Overseer - if the Overseer is still alive, he relinquishes the role. Amata will show regret and sorrow if you had to kill the Overseer, or excitement and amazement if you managed to persuade her father to step down without violence. If you talk to her she will then 'ask' you to leave the vault permanently even if you instead persuaded her father to stand down without violence and will provide you with the modified utility jumpsuit (only if you didn't use violence). You may randomly encounter Susie Mack in the Wasteland. You can talk to her and she will give you purified water but say that you still cannot return. Butch will end up in Rivet City at The Muddy Rudder.

Destroy the Vault
For those with a more nefarious attitude toward the vault, destroy the vault entirely. This requires hacking the (hard) computer in the sub-basement or steal the Vault 101 maintenance password from Stanley, the maintenance man, who can be found wandering around the cafeteria/dorm level. Go into manual override mode and perform a flush and a purge. This will flush the water chip, resulting in a catastrophic system failure (if Stanley is performing maintenance on the system, as he tends to do, the resulting explosive malfunction will kill him). Everyone is forced to evacuate the vault and you will see them spread out in the Wasteland (you lose Karma for this).

Doing this nets no rewards of any kind except bad karma. You can, of course, still loot the Vault.

Failure
Killing the overseer after getting the vault either open or closed results in failure of the quest itself. This also causes the vault to be left open and you can come and go as you please, but all residents will turn hostile. A message will appear explaining that Vault 101 has been 'thrown into chaos'. If you decide to make it a home-away-from-home, be aware that even after you've killed all the people, the place will become infested with radroaches.

Behind the scenes
Portions of Amata's speech to the Lone Wanderer when he or she leaves are strikingly similar to the speech given to the Vault Dweller at the end of Fallout, even the number of ellipses used in each (bold quotes specifically).

Note: The above dialogue only appears if the Lone Wanderer chooses to resolve the problem by killing the Overseer. Resolving the problem diplomatically results in a different dialogue that does not reference the original Fallout.

Bugs

 * When attempting to reason with the Overseer and convince him to step down, he refers to the player as a "young man," regardless of the Lone Wanderer's actual gender.
 * If you entered the Operation: Anchorage simulation when the signal was available, but had not activated the quest, the signal will disappear upon exiting the simulation preventing you from ever starting the quest. The same thing happens upon going to, and returning from, Point Lookout - but if this happens, going to The Pitt and returning directly to Megaton/Vault 101 might reactivate the signal. Also, the signal might not be available for those who have installed the expansions "Operation: Anchorage" and "The Pitt" just after doing the quest, "Waters of Life." After finishing the quests from "The Pitt" you can go to Megaton or Vault 101, open the radio screen on your Pip-Boy, and listen the Vault 101 distress signal to start the quest.
 * It is possible that the final objective (Leave Vault 101 forever) will stay marked as unfinished, even after you've completed the quest.
 * If you choose to end the vault troubles by sabotaging the vault, the vault door will remain open, allowing you to come and go as you please. If you inspect the vault for any present dwellers, you will notice that Beatrice Armstrong is no longer present at the surgery table (but Andy is still present), and Mr. Brotch is no longer held up in the jail cell (if you decided not to free him in the quest). The jail cell door remains locked.