I Know You

 is a stranger side-mission in Red Dead Redemption.

Story
The player will encounter a strange man who seems to know a lot about Marston's past and claims to know him from your days running with the Dutch van der Linde Gang. He asked the player to go to Thieves Landing to check on a friend of his, who is drunk and contemplating cheating on his wife. The man does not explicitly say to stop him, just to advise him on how to best proceed.

Whether the player stops the friend or lets him continue, the Strange man will comment on the decision in the second encounter, although it does not affect the outcome.

The player meets the Strange Man again in Nuevo Paraiso, where he suggests the player either help a nun who is collecting donations in a dangerous area, or simply rob her.

The third and final confrontation with the Strange Man takes place outside Beecher's Hope, where after more enigmatic dialogue, such as him not knowing his own name, collecting accounts of a sort, and being damned by many people. John loses his temper after asking the Strange Man for his name and fires on him, but the man is not affected by the bullets and walks away.

If this final encountered is not completed prior to the mission The Last Enemy That Shall Be Destroyed, players cannot complete this stranger mission. However this does not prevent getting 100% completion.

Walkthrough
After meeting the Strange Man, head to Thieves Landing and go to the saloon. The drunk friend should be on the porch. Players can either dissuade the drunk friend from cheating on his wife, or give him $15 to persuade him to cheat on his wife. Giving him the money will cause the player to lose Honor.

After the Fort Mercer missions, he can be found in Mexico, giving players the choice of donating $10 to, or robbing a nun.

There is one last interaction with the Strange Man, on top of the hill overlooking the Marston Ranch.

Interpretations
For more information on the popular explanations and thematic interpretations of this strange mission, please visit the Strange Man character page.

Trivia
• In his last encounter the stranger predicts John Marston death by saying 'nice spot' while standing on John Marston's future grave.