Arthur Maxson

Elder Arthur Maxson, registration MX-001E, is the last descendant of Roger Maxson in the year 2287. Maxson and his ancestors are the founders and traditional leaders of the Brotherhood of Steel. He serves as the primary antagonist of Fallout 4 if the Sole Survivor sides with the Institute.

Fallout 3
Arthur was born in 2267 and is a descendant of the legendary Roger Maxson, founder of the Brotherhood of Steel. His father, a high-ranking Paladin serving just outside the New California Republic, was killed in battle, and his mother, Jessica Maxson, sent the boy east to be raised under the tutelage of the respected Elder Lyons. Arthur tended toward timidity, which was the main reason his mother sent him to the Citadel.

From his computer (which the Lone Wanderer can hack without Karma penalties), the Lone Wanderer can discover that young Arthur enjoys writing stories, has a crush on Sarah Lyons (because she taught him to kill a man by stabbing him in the kidneys), and that there is a Guns and Bullets magazine underneath a bed in the den.

Fallout 4
After the events of Fallout 3 the East Coast Brotherhood of Steel faced a leadership crisis after Elder Owyn Lyons died of natural causes and his daughter Sarah Lyons was "killed in combat" shortly thereafter. The East Coast Brotherhood repeatedly appointed and deposed numerous ineffectual Elders until Arthur Maxson was appointed Elder of the East Coast Brotherhood by the West Coast Elders in 2283 at the age of sixteen, the youngest in the history of the Brotherhood, after displaying exceptional skill as a capable warrior and diplomat by defeating the super mutant leader Shephard and brokering peace with the Brotherhood Outcasts, bringing them back into the fold.

Arthur returns in Fallout 4 as the young and idealistic, but capable leader of the Brotherhood in the East Coast. He has established an amalgam between the ways of his predecessor and tutor Elder Owyn Lyons, who was using technology to help others, and the traditional Brotherhood approach of coveting and preserving advanced technology to protect people from abusing it. As a result, he is much more lenient about technology being in the hands of outsiders, and allocates teams of soldiers to combat dangers that would otherwise harm or kill the people of the wasteland, while he has other teams scouring the ruins for technology that could be misused in the wrong hands. Maxson also strongly insists that the Brotherhood has the best interests of the Commonwealth in mind.

As a charismatic leader and a skilled tactician, Arthur has won the respect and admiration of his men through his numerous exploits. When he was 10, he killed a Super Mutant in a training mission. He owes his scar to a fight that he led alone against a deathclaw at the age of 13, an opponent that even BoS veterans advise not to face single-handedly.

Maxson is loved and admired throughout the Brotherhood. On the West Coast, some in the Brotherhood have even gone so far as to worship Maxson, much to his dislike. The Western Elders have these cults hunted down and uprooted.

He deeply cares for everyone under his command, as he was heavily reluctant to allow Ingram into the field as a field scribe despite Knight-Captain Cade's professional opinion that due to her power armor frame (which replaced her legs and much of her lower torso), she was more suited for combat than scribe-work, in fact probably better suited than any Knight they could muster. Additionally, he explicitly ordered that all technology was to be traded for food and medicine, and violent confrontation was to be a last resort, which drastically sets him apart from the West Coast Brotherhood, who used violence as a first resort. It shows not only that he doesn't wish to risk the lives under his command, but he does genuinely care about the people of the Commonwealth.

He also approved a request by Senior Scribe Neriah to develop an alternative and more effective to the Pre-War Rad-Away, which also shows that he has carried on Lyons' efforts of improving technology as opposed to simply hoarding it, which remains the West Coast's goal, as can be seen through a conversation between Nolan McNamara and Veronica Santangelo in Fallout: New Vegas.

Fallout 3
He can usually be found in the Citadel B ring, where his room (and personal terminal) is located.

Fallout 4
Maxson, along with the Prydwen, will show up in the Commonwealth once the quest Reunions is completed. He can usually be found in the Main Command Deck of the Prydwen, and may also go to his room.

He will join the Brotherhood attack on the Institute during the quest Ad Victoriam, and become a temporary follower in The Nuclear Option.

If, however, the player decides to side with the Institute, then during the quest Airship Down he will emerge from a crashed Vertibird as the only survivor, in his personal Elder Power Armor wielding his unique Gatling laser. The player will have no choice but to either kill him or serve as a distraction from the Synth Virus, and after Liberty Prime is infected with the Institute virus, Liberty Prime will either instantly kill Maxson (all of his attacks are instant kills) or miss him.

In the Minutemen main quests, he serves as a mentioned only antagonist, as Maxson is killed when their artillery blows the Prydwen out of the sky.

In the Railroad main quests he is largely mentioned only until Rockets' Red Glare, where he can be confronted while or after sabotaging the Prydwen.

If the Brotherhood is victorious, then Maxson will advise that, as the Sole Survivor holds the rank of Sentinel, while they are free to carry out their own missions, to keep the Brotherhood's interests as a whole at heart.

Quests

 * Tour of Duty: After Paladin Danse brings the Sole Survivor to the Prydwen after its arrival in the Commonwealth, Maxson promotes them to the rank of Knight and asks them to tour the Prydwen and get to know her crew.
 * Show No Mercy: Maxson orders the Sole Survivor to clear Fort Strong, a cache of Fat Man ammunition, from its super mutants occupiers.
 * From Within: Maxson orders the Sole Survivor to find Doctor Madison Li in the Institute and convince her to work for the Brotherhood of Steel
 * Blind Betrayal: Maxson orders the Sole Survivor to execute Danse, who turns out to be a synth.
 * Ad Victoriam: Maxson appears as Liberty Prime reaches the C.I.T. ruins, helping the Brotherhood against the Institute synths.
 * The Nuclear Option: Maxson follows the player inside the Institute and helps them clear out the Institute.
 * Rockets' Red Glare: Maxson defends the Prydwen against the Sole Survivor, sent there by the Railroad to plant explosives in the airship.
 * Airship Down: Maxson appears in a full set of T-60f power armor and his unique Gatling laser at the Boston Airport to defend it from the Sole Survivor and the synths as they try to hack Liberty Prime.

Fallout 4

 * (Said in response to the Sole Survivor after telling him they defeated Institute for the people of the Commonwealth.)

Appearances
Arthur Maxson appears in Fallout 3 and Fallout 4.