Sarah Lyons was born in 2251 in the Brotherhood of Steel's Lost Hills bunker in California. In 2254, the Brotherhood of Steel ruling council decided to send a contingent of soldiers under the command of Star PaladinOwyn Lyons to the East Coast with a mandate to recover all advanced technology from the Washington, D.C. area. Three at the time, Sarah joined her father on his journey east to the Capital Wasteland (her mother having died several years earlier). Since their arrival and establishment of a permanent base at the Citadel, Sarah trained to be a warrior.
By 2277, Elder Lyons' daughter Sarah is a grown woman and one of the Brotherhood's finest warriors. Brotherhood through and through, she is as dedicated and decorated as her father when he was younger. In fact, she’s the only member to have achieved the illustrious rank of sentinel, and now commands her own elite squad, Lyons' Pride.
Sarah Lyons fought for her father's chapter of the Brotherhood of Steel until his death. After, she would become the new elder of the East Coast Brotherhood of Steel. Despite her critical leadership position, Sarah continued to fight on the frontlines. Shortly thereafter, she was killed in battle and Lyons' Brotherhood of Steel would stumble to find an effective leader for several years until the rise of Elder Arthur Maxson.
Sarah is loyal to her father, but her superior attitude to wastelanders is more typical of those in the Brotherhood with lingering sympathies for the Outcasts. She has little patience with "civilians" stumbling into the line of fire. Her attitude towards InitiateReddin suggests she is not convinced that wastelanders should be recruited into Brotherhood ranks.
Following in His Footsteps: The Lone Wanderer encounters Sarah while traveling to the GNR building plaza. The player character will find her squad not far from the Tenleytown/Friendship station exit to Chevy Chase North. When the player character approaches her, Sarah will not trust them but will allow them to follow behind them to the GNR studios. Upon reaching the GNR building plaza, the Lone Wanderer and Lyons' squad will be attacked by super mutants and a super mutant behemoth. Lyons will then enter the GNR building with the remainder of her squad. While there, she can be talked to and will thank the Lone Wanderer for their help if appropriate.
The Waters of Life: Sarah accompanies her father when he receives Dr. Li, her team, and the Lone Wanderer at the Citadel's courtyard. Once the Elder has finished his conversation with Li, Sarah will unsuccessfully try to convince her father to let her team attack the Enclave immediately.
The American Dream: Once the Lone Wanderer has escaped from (and possibly destroyed) the Enclave's base at Raven Rock, Sarah will once again attempt to convince her father to let her team try to retake the Jefferson Memorial. While Elder Lyons initially refuses, once he hears that the Enclave has acquired the G.E.C.K. and thus possess the technology to reactivate Project Purity, he agrees to greenlight the mission.
Take it Back!: Sarah, after inducting the Lone Wanderer into the Pride, briefs her team on the mission to come. She personally accompanies the Lone Wanderer into the Jefferson Memorial rotunda for the final confrontation with Colonel Augustus Autumn and his handful of personal guards. Based on the Lone Wanderer's choice, Sarah Lyons will:
Watch the Lone Wanderer's selfless act of sacrifice in choosing to enter the chamber and mourn their inevitable demise (unless Broken Steel is installed).
Enter the chamber herself, sacrificing herself in place of the Lone Wanderer.
Wait until the purifier explodes.
Who Dares Wins: After the player character escapes from the mobile base, Sarah Lyons will appear again (unless she was killed) and pick the Lone Wanderer up in a vertibird, taking them back to the Citadel.
She will comment if the player character is wearing power armor when fighting the behemoth in the GNR plaza, saying they can wear it for helping them defeat it.
If the Lone Wanderer activates the purifier themself, or uses Fawkes, Sergeant RL-3 or Charon to start it; it is revealed that an energy spike knocked her and the Lone Wanderer unconscious. Two weeks later after the Lone Wanderer wakes up, she's still in a coma, "unresponsive but stable."
If Lyons activates the purifier, she will be killed by the radiation and does not appear again.
After completing all the main quests, if the Lone Wanderer chooses to destroy the Enclave, she will comment that if things had been different, they could have had time to become friends.
If the Lone Wanderer betrays the Brotherhood instead and launches an orbital strike on the Citadel, she and the other Brotherhood members who picked the Lone Wanderer up will attack in a fury, calling them a traitor. It is then possible to kill her, as she will no longer be essential.
Although her stats are normally on par with a normal Brotherhood of Steel paladin, during the final quest "Take it Back!" her health is increased to 505, giving her extremely high durability on par with Star Paladin Cross while she fights alongside the player character during the game's final battle. Additionally, as a plot-critical non-player character, she cannot be killed during the course of the game, merely knocked unconscious.
Sarah Lyons is coded as a non-player character companion, and therefore uses up ammunition for her weapons, unlike most standard non-player characters. She has more than 100 microfusion cells in her inventory to prevent her from running out of ammunition under normal circumstances.
After destroying the Enclave at the end of Broken Steel, the first thing she will say to the Lone Wanderer afterward is, "When I first saw you long ago in that alley Chevy Chase, I thought you were just some trashy Wastelander. I'm glad to see I was wrong.", even if the Lone Wanderer never completed the Galaxy News Radio quest.
Due to her looks, Sarah has a number of male admirers, including the young Arthur Maxson.
She, along with Amata and Owyn Lyons, is one of three characters in the game to have "Very Good" Karma.
The information about her death can be found in Proctor Quinlan's terminal on the Prydwen.
In Fallout Shelter she is portrayed wearing T-51 armor, even though she and all other Capital Wasteland chapter Brotherhood of Steel members wear T-45.
PCPlaystation 3Xbox 360 At the end of the game Sarah Lyons can glitch into either saying that "the control room still isn't clear" or repeat the phrase "Steel be with you!" [verified]
Xbox 360 After The Waters of Life, before speaking to Rothchild to start the quest Finding the Garden of Eden, Lyons will appear on the road leading from Arlington Library to the Flooded Metro, walking along the road to a point past the Nuka-Cola plant. [verified]
↑ 1.01.1The Prydwen terminal entries: "When Elder Owyn Lyons died, care of young Arthur Maxson passed to Sarah Lyons, Owyn's daughter, who was then named Elder in his place. But when Sarah fell in battle shortly thereafter, things became complicated."
↑Fallout 3 Official Game Guide Game of the Year Edition p.96: "Sentinel Sarah Lyons Sarah, 26, was born in the West Coast Brotherhood of Steel headquarters. At the age of seven, she accompanied her father on his journey east to the Capital Wasteland (her mother having died several years earlier). Sarah Lyons is Brotherhood through and through, as dedicated and decorated as her father when he was younger. She commands a group of soldiers assigned to patrol the Washington, D.C., Mall area and operates out of the G.N.R. studio outpost." (Fallout 3 Official Game Guide Game of the Year Edition Wasteland Census)