How to unlock: Talk to Captain Kells on Prydwen (M7,2). The quest will become available once you complete the Duty or Dishonor quest and after you start the Liberty Reprimed quest.
- Kill Virgil
- Report to Captain Kells
A Loose End quest will start automatically after you complete the Duty or Dishonor quest, but only under the condition that in the Brotherhood's main storyline you have at least started the Liberty Reprimed quest.
Kells will ask you to kill Virgil, the supermutant - researcher who can be found on the glowing sea. Go to the Rocky Cave location that is advanced to the southwestern edge of the map. Walk inside. After a short conversation Virgil will attack you. Kill him and destroy few robots that will become unfriendly towards you. Now go back to Prydwen ship and talk to Kells. He will give you a helmet for the power armor.
Quest rewards: Experience points, power armor helmet.