Brian Virgil

Brian Virgil is a super mutant living in the Commonwealth in 2287. Living initially in the rocky cave, he helps the Sole Survivor find a way into the Institute.

Background
Dr. Brian Virgil was a member of the Institute at some point before 2287. He was working on an unknown project involving the Forced Evolutionary Virus and the creation of Super mutants in the bioscience division, but went rogue. He then escaped to the Glowing Sea and infected himself with the FEV virus to aid in protection from radiation for his escape.

Quests

 * The Glowing Sea: After heading through the Glowing Sea and talking to Virgil about needing his help, Virgil will ask to get an experimental serum that he claims will make him a human again, but isn't sure if it exists or not. The player character must agree to this if they want to complete The Glowing Sea and continue the main story line. The player character will have to go to the FEV labs in the Institute to retrieve the serum. The FEV lab is located within the Bioscience section of the institute, locked behind a laser-wall and a Master Terminal. There is another entrance to the FEV labs from the Bioscience section, if you don't have the hack level to bypass the Master Terminal. But, you will need a higher level lockpick. To get to the second entrance, turn immediately right after entering the Bioscience section and head through the supply room and then down the corridor. There are several laser turrets and an assaultron through a series of halls, rooms, and locked doors that lead to the actual lab, though FEV labs will be displayed once you get into the general area (note that the scenery will be much different, dark and abandoned). You'll know it when you reach the actual lab, there are several water tanks that contain super mutants. The serum is in the corner.
 * A Loose End: Unless convinced to spare him through a charisma check, Kells will order the Sole Survivor to kill Virgil.

Effects of player's actions
After getting the serum, the player character has two options: If the player character gives Virgil the serum and waits for around a week, they can go back and see that Virgil is now a normal human. If the player character destroys the Institute, Virgil will no longer want to speak with you and will ask you to leave.
 * They can simply give Virgil the serum, and certain companions will react differently to this choice. For example, Piper would like it if you did, but Danse won't like it at all.
 * They can also lie to Virgil through a speech check, claiming that it wasn't there, which will prompt him to request the player to kill him.
 * If the player destroys any of Virgil's turret defenses, spotlight, or Protectron prior to returning to complete the quest "The Glowing Sea" you will immediately fail the quest upon re-entering Rocky Cave with the serum.
 * If upon getting the serum the player waits before bringing it to Virgil for around a week, he (Virgil) is then found completely turned hostile and quest "The Glowing Sea" will immediately fail upon re-entering Rocky Cave.

Appearances
Virgil appears only in Fallout 4.