How to handle PCs lying to/acting sneaky around other PCs?

Question

In Dungeon World, how is it determined if a PC knows whether another PC is lying?

For example, say Peter the Paladin asks Terry the Thief where he got his shiny new knife. Terry responds nonchalantly "I just found it in the forest", while he (and the players) know very well that he stole it off a nobleman last night.

I see the following options:

• The player being lied to decides. The player of Peter the Paladin uses what he knows of the in-game fiction (how much Peter trusts Terry, whether or not Peter knows Terry has a history of stealing) and makes a judgement on whether or not Peter believes him. Having the player decide would probably work fine in my group, but could lead to situations where the thief's player thinks it's unfair that other players can just say that they don't believe him, even when his character is supposed to be a good liar.
• The thief has triggered the Defy Danger move. Terry the Thief is defying danger, with the imminent threat being Peter the Paladin not believing his lie and earning his distrust. Have Terry roll and interpret the results according to the move.
• The paladin has triggered the Discern Realities move. Peter the Paladin is closely studying Terry to work out if he's lying. Have Peter roll and follow the results of the move.
• Make a GM move. If everyone is looking to the GM to see if Peter beleives Terry, this would mean it's time for the GM to make a move. You could 'tell them the requirements or consequences and ask', by offering Terry a choice. E.g. Terry can tell that Peter is not quite believing his story, he could alleviate Peter's suspicion by going on a quest to return the knife to its original owner, or by showing Peter where he found the knife in the forest.

All of these seem like valid options to me, and it's possible that any of them could apply, just depending on how the fiction is described.

Is there a correct option in terms of how the Dungeon World rules work?

Similarly for acting sneaky, lets say Terry is trying to sneak out of camp to do some stealing in the middle of the night, and Peter is on watch. How do you determine if Peter spots him? The same options as above seem to apply.

Answer 1

All of your examples could apply... in different cases. As a rule in Dungeon World, go straight with what the players describe happens.

• The player being lied to decides. Yeees, in part. If the group already trusts each other implicitly and there is nothing 'fishy' about the story, the player that is being lied to is perfectly in the right to just say 'oh, ok, cool you found that in the forest' Same with a character who just met this other dude and is inherently suspicious of any and all people he meets. He would just... not believe this guy. But! If the situation is not as clear cut or your players have issues figuring this kind of stuff out on their own, definitely go with either:

• Thief triggers defy danger move Example trigger: "I know Peter doesn't trust me and he has a stick up his ass anyway, so I try to make this go as smooth as possible, really work him!" He is the actor in this case, the first one to trigger something so to speak. If Peter is indeed suspsicious, he can of course interfere :)

• The paladin has triggered the Discern Realities move. This is the thief is not making sure Peter is being swindled just right and/or paying attention to tell a convincing story. Peter isn't sure whether to believe what the thief is so casually telling him and so starts closely studying the shifty guy and his mannerisms. Of course, once more the thief can notice this behavior in turn "Terry, you notice Peter eyeing you up and down with that frown of his... what do you do?" (IF, again, he is paying attention and not going off elsewhere/doing other things) and can add to his story, meaning thats another interfere roll right there.

Point is, always listen to what the players are describing. If they aren't describing enough, ask questions and use the answers :)