We talked before about Intimidation and some of the problems with it as a skill when it comes to working on players and how different people react. There is another skill that can be just as problematic but often floats under the radar. That skill is 'Charm' or skills like 'Charm' (i.e. Seduction) and while it is a softer touch it does have some intricacies I'd like to talk about today.
The Fastest Way To Make A PC Suspicious...
...is to roll some dice after a social interaction and then tell the player that they like/trust the person they were talking to. This is a natural reaction. See, the player knows you rolled dice and that means a skill check of some sort. That tips them off that the NPC they're dealing with has that skill - means they're likely important - and that the NPC took effort to make them, the PC, like them. Couple that with the fact that generally people only try to make you like them when they need/want to use you for something, and is it really a surprise that the player is suspicious?
You Can't Make Me Like You
Much like how some people respond to intimidation differently, alot of folks get upset by the concept that they're being told who their character does or doesn't like. Now, granted, there are some situations for this. Someone who is very biased against some group (say a "prim and proper" sort vs. a greaser in a 60's style game) is going to be suspicious and likely won't like someone no matter how charming they are. The problem is is that that sort of bias should really be reflected with a large situational modifier, not reaction after the roll.
After all, all the greaser would have to do is convince Mr. Prim and Proper that he wasn't like those other guys. He's different and understands.
A Soft Touch
Charm is, ultimately, a soft touch in the social interaction. It is also best used as a soft touch in terms of gameplay also. Saying someone is "likeable" or "puts a good face forward" can get the point across better. People respond badly to brute force, so don't use brute force. Shape other words around how you describe things. "She wants to help you," "He gives a genuine smile," "She leans forward slightly, giving you her full attention." All of these are great ways to show a person being rapt, friendly, and engaged with something without bludgeoning the player over the head with it. Better yet the phrases also help paint the scene just that little bit more.
Oh, but what about when the player sees through? Well, the soft touch can help there too. Instead of "She wants to help you," you can say "She looks like she wants to help but you get the sense she's holding something back." Instead of "He gives a genuine smile," you can say "He gives a broad smile but it doesn't quite reach the eyes the way it should." Finally, instead of "She leans forward giving you her full attention," you can say "She leans forward as if in rapt attention, but you get the sense there's something else on her mind as well."
In all those cases you show that there is more going on than the face being put forward, but you don'tspill the whole can, just like you don't force the issue when it is going in the Charmer's favor.
NPC vs. PC
Fortunately, with NPCs things get a bit simpler. When a NPC gets charmed you can take it more directly and apply it that way.
What's The Harm
The other way you can use charm in social interactions is with the "What's the harm?" These work in much the way you are probably thinking. Information just slips out. After all, what's the harm if you tell the cute guy in the tavern that the Baron has been doubling the guard near the treasure vault, or that the servants keep leaving the side entrance to the laundry open. These are things that can just slip out.
On the player side you can leak the information for them and then tell them. This works becaue generally people don't realize they've slipped up until after they do it. That said, never do this without giving the player a chance to roll to defend unless you either 1) have a way to pay the player like a FATE point or something or 2) know the player specifically may be ok with the complication. You also want to let them know that what just slipped out did just slip out. Then see how suspicious they get.