A self-styled inventor, 24-year-old Moira grew up with an uncommon curiosity about the world in the trading community of Canterbury Commons. 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. 
After writing the guide (with the help of the Lone Wanderer), it became considerably popular, since it managed to reach places like the distant Mojave Wasteland in less than four years.
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 be able to repair, lacking an option to buy or sell items.
If you decide to blow up Megaton, she will not die; instead she will become ghoulified. If you started the Wasteland Survival Guide quest, or met her to receive an armored Vault jumpsuit, you will have to visit the Megaton Ruins to find her. If you hadn't started it, she can be found in the Underworld, whereupon she will claim she was 'out-of-town' during the detonation, and apparently unaware of her recent affliction. Depending on how you break 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 increase her Repair skill to 54 (72% condition). You will also lose Karma and gain the Dream Crusher perk.
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 will walk there directly. This makes it extremely likely for her to be killed on the trip there, as there are several threats on the way.
Even though Carol in Underworld says it takes months or years to become ghoulified, Moira will instantly become a ghoul if you destroy Megaton.
If you hack her terminal, you can track her current experiments.
pcps3xbox360 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]
ps3 After killing Moira, opening her Craterside Supplies container, and stealing an item, a voice clip of her saying "Hey, that's valuable junk!" will play, even though she's dead. [verified]
ps3xbox360 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]
ps3 In a very rare occasion when the player kills Moira using an explosive or using the Bloody Mess perk would find (if afterwards detonated the atom bomb) Moira Brown floating outside Megaton in her 'corpse' pieces and any interaction with the Lone Wanderer is ignored. [verified]
pcps3 Attempting to trade with Moira Brown after she closes Craterside Supply each night results in her telling you that she's closed for the night. However, if you tell her "I'm looking to buy some things for my house," and then "Okay, let me take a look at your stuff," you can trade with her as if her store were open. [verified]