Mysterious Stranger (character)

The Mysterious Stranger is the individual that might appear if the player character has the Mysterious Stranger perk. He/she lends a helping hand in battles.

Background
The Mysterious Stranger in Fallout 3 and Fallout: New Vegas is heavily implied to be Farmer, and the father of The Lonesome Drifter. In speech, the Drifter will state that his father was a "mysterious" man, and that he was a "stranger" to his own family. The word mysterious appears right above stranger in the dialogue box. The Drifter carries a unique .44 magnum, which can be acquired by the Courier, that looks remarkably like the Mysterious Stranger's revolver; and when drawing the revolver, the same guitar notes that are heard when the Mysterious Stranger shows up are played, and a chord is played when the weapon is holstered. As of Fallout 4, the Mysterious Stranger is currently being investigated by Detective Nick Valentine, who has made note of his several appearances in other games of the series, and attempts to apprehend him when he appears.

Other interactions
There is a chance that Mysterious Stranger will appear as a temporary ally during random encounters.
 * $$\text{Chance of appearance }%=30+(2\times\text{Luck})$$

Other interactions
The Mysterious Stranger will appear out of nowhere to assist in battle by finishing off enemies. After the V.A.T.S. sequence finishes, he will disappear in a similarly abrupt manner.

Fallout Shelter
The Mysterious Stranger appears in vault rooms or elevators. He does not aid in battles, only appearing when the vault is not experiencing an incident. When selected, he disappears and the vault is awarded a random amount of caps. He must be tapped on to receive the caps.

Fallout 3, Fallout: New Vegas

 * A short guitar riff will play whenever the Stranger holsters or unholsters his weapon, as does the Mysterious Magnum.
 * He circles around the enemy shooting several times.
 * He can appear in water, and swim around. He will not shoot when this occurs.

Fallout 3

 * During the add-on Mothership Zeta, having the Mysterious Stranger perk opens up a unique dialogue option with Somah. "Maybe, if we're lucky, a friend of mine will show up to help us." To which she responds with confusion.
 * There have been cases of the stranger making movie like entrances and exits. An example is on the Anacostia Crossing escalators near Rivet City; he will walk up the escalators and shoot the enemy.

Fallout: New Vegas

 * He seems to have a son, The Lonesome Drifter, who wanders around the wasteland looking for his father.

Fallout 4

 * Unlike Fallout 3 and Fallout: New Vegas, The Mysterious Stranger no longer appears to be Asian. He now also sports a moustache.
 * The riff alerting to his upcoming presence is considerably different to previous games.
 * Nick Valentine is trying to arrest the Mysterious Stranger. Nick has a short log containing everything he knows about the Stranger in his office, and if the player has him as a companion, Nick will exclaim in frustration as the Stranger slips away.

Appearances
The Mysterious Stranger appears in Fallout, Fallout 2, Fallout 3 and all its add-ons, Fallout: New Vegas and all its add-ons, Fallout 4 and Fallout Shelter.

Behind the scenes

 * The Mysterious Stranger is inspired by the trenchcoat-clad figures of 1940's and 1950's film noir.
 * In Fallout 3 and Fallout: New Vegas, The Mysterious Stranger had a unique .44 Magnum; Mysterious Stranger's .44 magnum that could only be obtained via console commands. It deals up to 9000 damage, making it the one of the strongest weapons in both games.

Fallout 3, Fallout: New Vegas

 * If the Mysterious Stranger appears and there is a wall or other obstacle between him and his target, he will not take a shot. This will sometimes lead to you being stuck in V.A.T.S. permanently, necessitating a reload of an earlier save.
 * This may also happen if your target is swimming as he will not be able to draw his weapon and will swim around possibly rendering you stuck in V.A.T.S.
 * If the enemy is near a cliff and a weapon is used that knocks them off it without killing them, the Stranger may spawn in the air off the cliff and fall to his "death" as a result. As he is an "essential" character he will be rendered unconscious and the "Mysterious Stranger is Unconscious" message will appear on screen like any other essential non-player character. This will not prevent him from appearing to aid the player at a later date.
 * You can sometimes knock the Mysterious Stranger unconscious if you attack a nearby enemy in V.A.T.S. with an explosive such as a grenade.
 * After the Mysterious Stranger has killed his target, there may be a considerable delay in V.A.T.S. before he goes away and normal play is resumed. You and companions can still be attacked and may be be killed if there are other enemies around.

Fallout 4 - The Mysterious Stranger will appear but won't fire his shot, thus not killing the target and becoming permanently useless. Don't know what causes it. (PS4)

Gallery
Mystérieux Etranger (Personnage) Таинственный незнакомец (персонаж)