Wikia

Strangers are special NPC characters featured in Red Dead Redemption. Unlike core gameplay missions, these side-missions can be initiated and completed at any time. Strangers will request tasks or offer opportunities to the player.

Strangers are represented on the map by a question mark "?" icon. These question mark icons only appear on the map when the player is close to their locations. Visit the question mark icon to begin dramatic and sometimes dangerous chains of events.

Sometimes the player will be given a choice on how to complete the mission, and will yield positive or negative results for the player's fame and honor. Additionally, the successful completion of these activities will often reward players with cash.

Helping strangers, with the exception of the mission "I Know You", contributes towards 100% Completion.

Stranger Tasks

For more information on where to initiate these tasks, how to complete them, and all other details, please choose the desired one. Also, note that all of these articles contain a walkthrough and potentially major storyline spoilers.

New Austin

"American Appetites" - Randall Forrester • Grace Anderson • Ralph Anderson
"California" - Sam Odessa
"Flowers for a Lady" - Billy West • Annabel West
"Funny Man" - Jimmy Saint
"I Know You" - Strange Man
"Jenny's Faith" - Jenny
"Let No Man Put Asunder" - Alma Horlick • Peter Turner • Alan Harling • Rose Harling
"Lights, Camera, Action" - D.S. MacKenna • Silas Spatchcock
"Water and Honesty" - Andrew McAllister • Clyde Evans
"Who Are You to Judge?" - Jeb Blankenship • Unnamed Woman • Lucy

Nuevo Paraiso

West Elizabeth

"American Lobbyist" - The Blackmailer in Blackwater gazebo • The Gossiper in Blackwater Bank
"The Prohibitionist" - Abner Forsyth • Oliver Phillips
"Remember My Family" - Agent Howard Sawicki • Edgar Ross • Emily Ross • Phillip Ross
"The Wronged Woman" - Clara LaGuerta • Harold Thornton • Elizabeth Thornton

Trivia

Strangers were first introduced in Rockstar games Grand Theft Auto IV, as Random Characters, and Bully, as NPCs that would appear randomly and request favors. They have been a feature of all Rockstar open world games since.

Tips

During Strangers' missions it may ask you to wait a couple days before you can encounter the next part of the particular mission, however, if you have auto-save enabled and complete one part of the mission it should auto-save. Reload the auto-save and it should allow you to continue on with the mission without having to wait any time at all.
Alternatively you can set up camp by using the "Campsite" item in your Kit in the select menu. Once you have entered the camp press the save (triangle/Y) button as if you were going to save and then press back (circle/B) to return to the campsite. This will cause 6 hours of game time to elapse as if you had actually saved. Move slightly away from the stranger and do the save/back trick a few times and then return to the stranger.