This guide will help you complete the Brotherhood of Steel Quest: From Within. This quest happens concurrently with the Main Quest: Institutionalized. Keep in mind that completing quests for particular factions can potentially impact the ending of the game, so make your choices and choose your faction wisely.
Locate Doctor Li
After speaking with Elder Maxson, you will be tasked with finding Dr. Madison Li during your investigation of the Institute. Maxson tells you to convince Dr. Li to work with the Brotherhood on a special project. From the main Institute courtyard, head through the door to Advanced Systems and locate Dr. Li in the lab to the right.
Speak to Doctor Li
After locating Doctor Li, tell her that you were sent to speak with her. You can indicate the Brotherhood if you wish. With a high enough Charisma level, you may be able to get her to trust you and agree to help with the Brotherhood project after a series of persuasive dialogue options. Otherwise, she will ask you fulfill a favor first before accepting your offer.
She will mention that she had a former colleague who was involved in a laboratory accident. However, since the details of her colleague’s death remain unclear, she asks you to find evidence that clarifies what happened to her colleague. Bring her this evidence, and she will consider aiding the Brotherhood on their special project.
Retrieve Evidence to Convince Doctor Li
Exit the Advanced Systems lab, and head down a path to the left leading to the Bioscience division. Enter the door to the Bioscience lab, and continue through the hallway on the right. Pick the lock on the FEV lab door at the end of the hallway. As you enter the next area, try not to trip the laser tripwire ahead of the doorway.
As you move through the formerly-sealed corridor, beware of the security turrets, synths, and an Assaultron that you will encounter along the way. Use a Stealth Boy to make traversing the corridor a bit easier. Eliminate the Assaultron, and continue through the passage. Once you reach the room guarded with another laser tripwire, disarm the tripwire and hack the terminal to the door on the right. This will lead to the main FEV laboratory.
The FEV lab contains a pair of super mutants preserved in large vats in the center of the room. Locate Brian Virgil’s Personal Log on a table next to a computer terminal to the right of the entrance. Pick up this holotape and head back to Dr. Li.
Bring the Holotape to Doctor Li
In the FEV lab, you’ll find a door on the opposite side of the room from where you found the holotape. This door leads back to the Bioscience Division. As you enter this door, there will be a laser grid at the end of the corridor that can be unlocked via the Lab Entry Terminal. Hack this terminal to clear the laser grid and enter the Bioscience Division. Now go back to the Advanced Systems lab to bring the holotape to Dr. Li. Once she reviews the holotape, Dr. Li will agree to assist the Brotherhood of Steel.
From here, you can continue with the Main Quest: Institutionalized or the Brotherhood of Steel Quest: Outside the Wire if you wish.
Report to Elder Maxson
When ready, travel out of the Institute and return to Elder Maxson on the Prydwen. Tell Maxson that you were able to convince Dr. Li to offer her services to the Brotherhood, and the quest will conclude.