Arthur Maxson

Arthur Maxson, commonly referred to as Elder Maxson, is the leader of the Brotherhood of Steel and one of the possible main antagonists in Fallout 4.

History
When the unit of Paladin Danse encounters massive energy readings in the Commonwealth, Maxson mobilizes the Brotherhood and invades the Commonwealth onboard the Brotherhood's airship, the Prydwen, intending to wipe out the Institute as well as their synths for good.

After the arrival of the Prydwen, the Sole Survivor can meet with Paladin Danse, who accepts him into the Brotherhood and brings him onboard the Prydwen, where Maxson is first met. Maxson orders the Sole Survivor to locate the Institute. Next to localizing the Institute, Maxson has another objective in the Commonwealth, finding Dr. Madison Li and reactivating Sentinel Prime.

At some point in the game, a furious Maxson calls the Sole Survivor before him. He reveals that Danse is a synth and has fled the Brotherhood and orders the Sole Survivor to hunt down and kill him. The Sole Survivor tracks Danse down to a bunker in the Commonwealth but whether he kills or spares Danse is up to the player. Should Danse be spared, upon leaving the bunker the player is greeted by Maxson, who furiously demands to know why Danse is still alive. The player can either execute Danse, spare Danse, tell Maxson to kill Danse himself or attack Maxson. If the player convinces Maxson to let Danse live, Maxson banishes Danse from the Brotherhood. The player is awarded the rank of Paladin no matter what outcome (except if he attacks Maxson). From this point, should the player choose Danse as a companion the Brotherhood is hostile as long as Danse travels with the Sole Survivor. Maxson then returns to the Prydwen.

to be added

Trivia

 * Maxson can be killed at any point in the game. Doing so earns the player the enmity of the Brotherhood and every member of the Brotherhood attacks on sight. This also prevents the player from continuing the Brotherhood storyline and achieving the Brotherhood ending.