A self-styled inventor, 24-year-old Moira grew up with an uncommon curiosity about the world in the trading community of Canterbury Commons. Sometime before 2263, she moved to Megaton. She's read almost every book that's come through the town. Although Moira's reading has taught her a wide variety of useful knowledge she has nearly no actual experience with the world, so she doesn't always understand how it can be applied outside of her workshop. After a recent accident with a domesticated centaur, Moira was inspired to write a book to help others survive in the wasteland and avoid similar dangers.
After the guide was completed (with the help of the Lone Wanderer), it achieved considerable popularity, managing to reach places like the distant Mojave Wasteland in less than four years. By the time of Fallout 4, the Wasteland Survival Guide had become a series, with multiple guides on subjects ranging from self-defense to hunting and farming, many of such issues can be found in the Commonwealth.
By 2297 she continued to run the Craterside Supply and the distribution network of the survival guide. On September 10, she began work on a biography of the Lone Wanderer.
Moira is the owner of Craterside Supply. She spends the day sweeping and trading as well as conducting odd experiments. She opens the store at 8:00 a.m. and closes at 8:00 p.m. The Megaton Craterside Supply store is also her home. She sleeps upstairs and if the Lone Wanderer is caught trespassing after hours she will become increasingly upset. The only time she will leave her shop is if Megaton is destroyed in the quest The Power of the Atom. If the Wasteland Survival Guide quest is completed before Megaton is destroyed she will instead stay near the entrance to the ruins and only has the option to repair equipment, lacking an option to buy or sell items.
If the Lone Wanderer blows up Megaton she does not die; instead she becomes ghoulified. If the Wasteland Survival Guide quest is started, or she is met and gives the armored vault jumpsuit to the Lone Wanderer, she can be found at Megaton ruins. If the quest was not started she can be found in the Underworld, whereupon she will claim she was 'out-of-town' during the detonation and is apparently unaware of her recent affliction. Depending on how the Lone Wanderer breaks the news to her she will either fall into despair or remain positive.
Convincing her that writing The Wasteland Survival Guide is a bad idea will result in a 30% discount on her wares and an increase of her Repair skill from 24 to 54 (72% condition). Karma will be lost but the Dream Crusher perk is given to the player character. This will also make her considerably less positive and more gloomy.
Moira's voice does not change after becoming ghoulified.
If the Lone Wanderer decides to blow up Megaton, Moira will not fast travel to Underworld, but instead walk there directly. This makes it extremely likely for her to be killed on the trip there. This is due to a combination of several threats on the way, a less-than-straightforward route, and Moira's observed unwillingness to defend herself.
Even though Carol in Underworld says it takes months or years to become ghoulified, Moira will instantly become a ghoul if Megaton is destroyed.
If her terminal is hacked her current experiments can be tracked.
Upon Megaton's destruction and encountering Moira after she becomes a ghoul, the Lone Wanderer can tell her "Don't take this the wrong way, but you got ugly real fast." This is a reference to the movie Army of Darkness.
The script notes imply that Moira Brown was previously called Lea Marsh.
The following is based on unverified behind the scenes information and is speculative and may not be accurate.
Moira's name might be a reference to the character Moira from On the Beach, a novel and film about nuclear war, like Fallout.
End of information based on unverified behind the scenes information.
Occasionally, Moira will not move from the Megaton ruins after the town has been destroyed if you have completed the quest Wasteland Survival Guide. She will stand in front of Megaton and can only repair. This will happen also if you complete the quest by depressing her. She will only say usual things like "Oh good. Someone who doesn't have a brahmin to wash up. That's a nice change." [verified]
To avoid this glitch, don't complete the "Wasteland Survival Guide", while doing that quest, complete "The power of the atom" quest and she while greeting you in Megaton and after some dialogue, she will start traveling to the Museum of History (Underworld).
Even when Moira is dead, opening her Craterside Supplies container, and stealing an item, she replies "Hey, that's valuable junk!", despite being dead. [verified]
In a very rare occasion if you save, kill Moira, and reload the save she will not be there and therefore rendered completely lost. [verified]
In a very rare occasion when Moira dies from an explosive or the Bloody Mess perk one could find (if one had detonated the atom bomb) Moira Brown floating outside Megaton in her 'corpse' pieces and any interaction with the Lone Wanderer is ignored. [verified]
Attempting to trade with Moira Brown after she closes Craterside Supply each night results in her saying she's closed for the night. However, if told "I'm looking to buy some things for my house," and then "Okay, let me take a look at your stuff," she can be traded with as if her store was open. [verified]
↑Moira's dialogue: "I'm pretty sure I remember a girl coming into town with that about ten, twelve years ago."
↑Fallout 3 Official Game Guide Game of the Year Edition p.86: "Moira Brown A self-styled inventor, 24-year-old Moira grew up in the trading community of Canterbury Commons with an uncommon curiosity about the world. She's read almost every book that's come through the town. Although her reading has taught her a wide variety of useful knowledge, she has nearly no actual experience with the world, so she doesn't always understand how it can be applied outside of her workshop. After a recent accident with a domesticated Centaur, Moira was inspired to write a book to help others survive in the Wasteland and avoid similar dangers. She just needs someone with real experience to test out her ideas and give her some real-world insight into life in the wastes." (Fallout 3 Official Game Guide Game of the Year Edition Wasteland Census)