Sierra Petrovita

 is a Nuka-Cola addict living in Girdershade in the year 2277.

Background
Sierra was born in 2251. She is blissfully and innocently unaware of her neighbor Ronald Laren's obsession with her or his unsavory intentions with her.

Daily schedule
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.

Quests

 * 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 you an Ice Cold Nuka-Cola and ask you to gather 30 Nuka-Cola Quantums for 40 Bottle caps per bottle which adds up to 1200 caps. Completing the quest her way grants the player good karma.
 * Mississippi Quantum Pie: After completing "The Nuka-Cola Challenge", she can make you a Mississippi Quantum Pie out of 1 Nuka-Cola Quantum, 1 bag of Flour and 1 bottle of Vodka.

Appearances
Sierra Petrovita only appears in Fallout 3. Her house can be entered in Fallout: New Vegas by teleporting into it through the console. No sign of Petrovita or her famous pie though.

Behind the scenes

 * She seems to have two different voice actors.

Bugs

 * If you kill Sierra and then steal items from her house, she may protest, even though she is dead. This woman is brutally passionate about her Nuka.
 * 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.
 * 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.
 * Sometimes Fawkes will attack Sierra when she takes the Quantum from your inventory, leaving Fawkes outside solves this issue.