Only in hostile random encounters, there is a chance that the character will gain a temporary ally in a leather jacket (male with a male character and female with a female character), details depend on the PC's level.
Unlike in Fallout, the Mysterious Stranger will now leave the map of the random encounter directly after ending combat. A few exceptions to this are caravan encounters, and encounters with a cave included.
If attacked, the Mysterious Stranger will attack back; however, he will be friendly again during the next hostile random encounter.
The inventory of the Mysterious Stranger is different at each random encounter.
If the Mysterious Stranger dies, he will never come back.
The Mysterious Stranger perk in Fallout is stronger than in Fallout 2, since the Mysterious Stranger is already at their maximum statistics and their plasma rifle is more powerful in Fallout than the H&K G11 that the Fallout 2 equivalent has.
In Fallout 2, they can be encountered in any random encounter. This also includes simply stopping on the map, and entering the map via the inverted triangle at your location.
The Mysterious Stranger with a hunting rifle actually spawns shotgun shells as ammunition instead of .223 FMJ. As such, the Mysterious Stranger only has the 10 shots already provided in the clip. [verified]
In Fallout 2, if the game is saved during a random encounter when the Mysterious Stranger is still on the map and then reloaded, the Stranger will remain in place. [verified]
Gives you your own personal guardian angel... armed with a fully loaded .44 magnum. With this perk, the Mysterious Stranger appears occasionally in V.A.T.S. mode to lend a hand, with deadly efficiency.
If the last target at the end of V.A.T.S. sequence has 150 health or less, there is a 10% chance that the character will gain a temporary ally in a fedora and overcoat that will finish off that target using his unique .44 magnum.
In the Fallout 3add-onMothership Zeta, when first arriving aboard Zeta, having the Mysterious Stranger perk opens up a new line of dialogue with Somah, with the option "Maybe, if we're lucky, a friend of mine will show up to help us."
In Fallout 3, "mesmerizing" non-player characters with a Mesmetron in V.A.T.S. will sometimes make the Mysterious Stranger appear, resulting in him killing the victim.
The Mysterious Stranger will sometimes seek out other hostiles while in V.A.T.S., after he has killed the targeted one.
His appearances have a counter ("Mysterious Stranger Visits") that is displayed randomly during the loading screens of Fallout 3, and on the Pip-Boy 3000 under the "Stats tab - General" in both Fallout 3 and Fallout: New Vegas.
In Fallout: New Vegas, the Miss Fortune perk functions in the same way as this perk, but with different effects in combat.
Both the Mysterious Stranger and Miss Fortune perks can be chosen by the player character, but the characters will not appear together in the same V.A.T.S. sequence.
When interrogating Silus at Camp McCarran, if he is being attacked by the Courier using V.A.T.S., Silus will be killed by the Mysterious Stranger should he appear. In this event, Carrie Boyd will not respond in any way to Silus' death.
It is possible to attack and even cripple the Mysterious Stranger by accident in V.A.T.S, but this seems to have no effect whatsoever.
The Mysterious Stranger can be incapacitated by nearby explosions, sending him flailing about.
If the Mysterious Stranger/Miss Fortune appears in gas-filled area, their gunfire will accidentally ignite the gas and hurt the player character and enemy alike.
In Fallout: New Vegas, after the Mysterious Stranger or Miss Fortune appears 15 times, the Friendly Help challenge is completed, increasing the probability for them to appear in combat much more often.
xbox360ps3pc The Stranger will sometimes be positioned unfavorably. This can include being stuck in a wall, being placed in water, being placed near a cliff, etc. This can result in his "death" (unconsciousness) or inability to effectively attack the enemy, or even in some cases to kill the player character if they are between him and his target. Because the Stranger never attacks, even if all enemies have died, he will be forever trapped inside the level geometry and the trigger to return the game to normal never happens. The only choice is to load a previous save. [verified]
xbox360 During V.A.T.S., it is common to hear the Mysterious Stranger jingle, even if he does not appear. This most likely happens at times when he would have appeared to finish off your enemy, but you killed the enemy instead. He may also have been affected by the bug above in some of these cases. [verified]
xbox360ps3pc Sometimes when the Mysterious Stranger appears, he does not shoot. He will just stand there, leaving you helpless. Another variant makes the Stranger reload his magnum for the duration of his attack. If it jams, he may not attack at all. This also happens if his target is killed prematurely by an explosion or by you or a companion. V.A.T.S. will remain active for an extended time, leaving you open for attacks by any surrounding enemies. [verified]
ps3xbox360 While in the Operation: Anchoragesimulation, the Mysterious Stranger will sometimes appear and then lie unconscious. When the V.A.T.S. sequence ends, gameplay will return to normal. [verified]
xbox360ps3pc At times, the Mysterious Stranger will aid you during V.A.T.S., but there will be a 5-10 second delay between killing the target and returning to normal gameplay. This can pose problems when fighting multiple enemies, as they will continue to attack both you and your companions during the delay. On occasion, this bug may cause normal play to not resume. [verified]
xbox360ps3pc Sometimes, the game can freeze in the zoomed-in style of V.A.T.S. when the Mysterious Stranger appears, making him stand there and watch. [verified]
xbox360 Occasionally, the game may register that the Mysterious Stranger has appeared (you receive a progress update) but he does not, nor does the opponent die. You remain frozen in V.A.T.S. unable to move or die. [verified]