Sierra is completely obsessed with Nuka-Cola and everything related to it. Her addiction to the soft drink started at or before the age of sixteen; since then, she has spent every bottle cap left by her parents in the pursuit of acquiring Nuka-Cola bottles, as well as assorted merchandise from vendors, travelers, and towns throughout the wasteland. She is largely incapable of holding a conversation without trying to steer the subject towards the soft drink.[Non-canon 1]
Ronald Laren is Sierra's only neighbor in Girdershade in 2277. Unfortunately for Ronald, who is attracted to Sierra's good looks, men are the last thing on Sierra's mind, unless they are bringing gifts in the form of Quantum Nuka-Colas. Ronald helped her acquire some Nuka-Cola artifacts for her hoard, and has even joined Petrovita's Nuka-Cola Fan Club as its first and only member. Sierra, styling herself as the President, Recording Secretary and Treasurer of her fan club, was delighted to have someone to share her obsession with, unaware of Laren's feelings for her. To Sierra, Ronald is simply a friend who keeps her safe from raiders.
Sierra managed to survive the treacherous Capital Wasteland and even expand her Nuka-Cola museum. By 2287, her obsession led her to the derelict Nuka-World, tracking down more artifacts for her collection. The ultimate goal is to win an ancient, forgotten contest, with the objective of finding ten hidden Cappys in the park, and a reward of meeting Bradberton in person. Although it assumed that he is long dead, what matters to Sierra is obtaining the original Nuka-Cola formula, thought to be located in Bradberton's office. The raiders who control the park tolerate Sierra's presence as long as she keeps to the market.
In Fallout 3, Sierra stays in her house all day drinking Nuka-Cola and doing other miscellaneous things. In addition, she hounds passing travelers for any trace of Nuka-Cola Quantum.
The Nuka-Cola Challenge: Sierra has her own Nuka-Cola "museum" (a display of her collection within her shack) which she gives tours in. After completing the tour she will give the Lone Wanderer an ice cold Nuka-Cola and asks them to gather 30 Nuka-Cola Quantums for 40 bottle caps per bottle which adds up to 1200 caps. Completing the quest her way grants good Karma.
She is the only non-player character known to be addicted to Nuka-Cola Quantum.
When asked about what kind of recipes she can make with Nuka-Cola Quantum, she says it's so rare, she only knows one. However, when she sends the Lone Wanderer off to get the 30 Quantums, she may say, "Hurry back, maybe I'll make some of my legendary Quantum Sorbet!" implying she knows more than one recipe.
She can reveal the location of Evergreen Mills through dialogue if asked if there is anything else interesting in the area (she warns the Lone Wanderer to stay away from it).
If told about Ronald Laren's sexual intentions for her, she will play it off as a joke on her.
In Fallout Shelter, it is possible to find an NPC with a randomly generated appearance bearing Sierra's name in random encounters in the wasteland.
In the Fallout 4 add-on Nuka-World, fulfilling John-Caleb Bradberton's request of letting him die at the end of the Cappy in a Haystack quest, after accepting Sierra's request to not kill him, will result in Sierra insulting the Sole Survivor before turning hostile, not only due to killing her idol, but also for lying to her, just to get her prized possession, the Nuka-World jumpsuit. Players intent on securing both the powerful Nuka-nuke launcher and her jumpsuit can either kill her, leave the area quickly after she becomes hostile, or use console commands to no-clip through the door.
In Nuka-World, Sierra's teeth appear to be rotten.
She pronounces her surname differently in Fallout 4 than in Fallout 3.
"It explodes in a huge blue flame too! How cool is that?"
If you kill Sierra and then steal items from her house, she may protest, even though she is dead. [verified]
If you fight any creatures outside of Sierra's house and then enter Sierra's house, you will not be able to communicate with her because she is fleeing. If you enter her house while enemies are still nearby, she will flee the house and disappear forever. Sometimes, she may run for cover at another house in Girdershade and can be found there, rather than fleeing town. [verified]
If you plant an explosive on Sierra and then ask her to make a Mississippi Quantum pie, she will start making it, but explode during the process. The player is stuck waiting for it to be made. Loading a previous save fixes this problem. [verified]
Sierra's Nuka-Cola kingdom
Sierra Petrovita in 2287 without her sunglasses
The completed quest objectives, where one saves Sierra from the ghouls
↑The Lone Wanderer: "Nuka-Cola collection? Wow!" Sierra Petrovita: "I have one of the... no, THE best Nuka-Cola collection in the Capital Wasteland. Heck, I've won the Nuka-Cola Fan Club Collection Award for the last ten years in a row!" (Sierra Petrovita's dialogue)
↑The Lone Wanderer: "What kind of stuff do you collect, exactly?" Sierra Petrovita: "Well, look around you! Toys, banners, stools... anything I can get my hands on really. My pride and joy is my perfect Nuka-Cola Machine. It's barely even scratched! Actually, I have to give credit to Ronald for donating some of it." (Sierra Petrovita's dialogue)
↑The Lone Wanderer: "Wait a minute. How many members are in your club?" Sierra Petrovita: "Well... only two right now. Me and Ronald. But membership is open to the public! You can join if you like!" (Sierra Petrovita's dialogue)
↑The Lone Wanderer: "There's a Nuka-Cola Fan Club?" Sierra Petrovita: "Yep, I'm the President, the Recording Secretary and the Treasurer. Once a year, we gather here in Girdershade to have a cook off using Nuka-Cola in the recipe. Last year I won with my "Poached Roach in Nuka-Sauce". Delicious!" (Sierra Petrovita's dialogue)
↑The Lone Wanderer: "Who's Ronald?" Sierra Petrovita: "Ronald? Oh! I'm sorry, I figured you met him already. He usually chats with people who enter Girdershade. He's my neighbor and my protector as he calls it. Imagine if some nasty Raider wanted to take my stuff... he'd show them a thing or two! He's such a sweetie, you should talk to him!" (Sierra Petrovita's dialogue)
↑The Lone Wanderer: "Tell me more about this Ronald guy." Sierra Petrovita: "He's a darling. Always watching out for me, and more importantly keeping the collection safe! Like once, there was these Raiders that came by. There were three of them and their leader was named like Lug-Nut or something..." The Lone Wanderer: "Um... Sierra..." Sierra Petrovita: "... so they like kicked in Ronald's door and he was like "BLAM" with his gun and one of them got all splattered. Then the other one tried to like hit him all in his head with some club and Ronald was so cool how he dodged it and shot the guy in the face. Then the Lug-Nut guy was in Ronald's face with the "I'll kick your ass" stuff and Ronald was like "Hell no..." and he punched the..." The Lone Wanderer: "Sierra! Please. I get it. He's tough." Sierra Petrovita: "Oh. Sorry! I get carried away sometimes. Well, you should definitely talk to Ronald. I bet he'd like to meet you. He's such a sweetheart." (Sierra Petrovita's dialogue)
↑The Sole Survivor: "You run a Nuka-Cola Museum?" Sierra Petrovita: "Absolutely! I've spent years collecting all the Nuka-Cola merchandise I could find. It's all on display at my home in a settlement called Girdershade. I give tours to anyone who stops by. And I can promise you this - you won't find another collection like mine in the Capital Wasteland, the Commonwealth, or any place else! Well, I'd stay and chat some more, but I've got to get back to my search." (Sierra Petrovita's dialogue)
↑Sierra Petrovita: "Nuka-World! I've always dreamed of coming here, and now I've finally made it. This place is amazing, don't you think?" (Sierra Petrovita's dialogue)
↑The Sole Survivor: "Bradberton... I remember that name. He was the guy who invented Nuka-Cola, right?" Sierra Petrovita: "Exactly! Wow, not a lot of people know that. At least not anymore.So to win the contest, you had to find ten images of Cappy, the Nuka-Cola mascot, hidden throughout the park. Each image has part of a code or something, and only these special glasses can reveal it. Now, I know what you're thinking. Bradberton's long gone, who cares about the contest anymore? Well I'm betting that somewhere in his office is the Original Nuka-Cola Formula! That formula was one of the great mysteries of the soft drink world, and it would be the crown jewel of my collection. If you can help me get it, I promise it'll be worth your while." (Sierra Petrovita's dialogue)
↑Sierra Petrovita: "You haven't seen anything that's, um, out of the ordinary around here, have you? Maybe something hidden? Shaped like a bottlecap?" Raider: "I thought we told you to keep your ass in the market. If you're looking for something, you can find it there like everyone else." Sierra Petrovita: "I'm not here for the market! I didn't travel hundreds of miles to go shopping." Raider: "I don't suppose you came here for a bullet in the brain either, so if you want to live, I suggest you stay where you belong." Sierra Petrovita: "Oh, you guys are real friendly, aren't you?" (Sierra Petrovita's dialogue)
↑Fallout 3 Official Game Guide Game of the Year Edition p.97: "Sierra Petrovita Sierra is a beautiful, 26-year-old, blonde who has no regard for anything but finding and consuming Nuka-Cola. She is absolutely fanatical about the blue drink and has been subsisting on the stuff for years. She has spent every Bottle Cap her parents left acquiring the drink from merchants, travelers, and towns spread throughout the Wasteland. Even though her looks are a desirable target for men, her personality leaves much to be desired. She is so oddly fascinated by Nuka-Cola that she will constantly shift conversations to speak about it and cares little for anything else. This is the subject of much anguish for the only other inhabitant of Girdershade." (Fallout 3 Official Game Guide Game of the Year Edition Wasteland Census)