Sentinel Lyons

Sarah Lyons is a Brotherhood of Steel sentinel and the commander of the Lyons' Pride squad in Fallout 3.

Background
Sarah Lyons was born in the West Coast Brotherhood of Steel headquarters. Her mother died several years before she accompanied her father, Elder Owyn Lyons, on his journey east to the Capital Wasteland.

In the ruins of Washington, D.C., she commands the Lyons' Pride, which she describes as "the best of the Brotherhood, bar none." Lyons decides who is allowed to be a part of the squad. Lyons is a role model for Arthur Maxson, a child living at the Citadel. He mentions that the sentinel is kind and has taught him a great deal, including taking him out once to kill super mutants. He admits that he accidentally shot her, but that her injuries were not serious. In a terminal entry, Maxson wrote that Sarah taught him how to kill a man by stabbing him in the kidneys, and that he thinks he is in love.

She became elder upon the death of her father but subsequently died in action. The Brotherhood of Steel struggled to find an effective leader for several years until Arthur Maxson became elder.

Quests

 * Following in His Footsteps: Upon reaching the GNR building plaza, the Lone Wanderer and Lyons' squad will be attacked by super mutants and a super mutant behemoth.
 * 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 possesses 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 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 death.
 * 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, if she survived, she will appear and pick the Lone Wanderer up in a vertibird, taking them back to the Citadel.

Effects of player's actions

 * 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."
 * 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.

Appearances
Sarah Lyons appears in Fallout 3 and its add-on Broken Steel, as well as a legendary dweller in Fallout Shelter. She is also mentioned in Fallout 4.

Bugs

 * 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!"
 * 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.