One approach I have been considering is to think about it more in terms of control of information. The parties then decide how they will act on beliefs informed by said information. (So the roll doesn't force them to feel frightened, it delivers to them frightening information.)
- Example, for intimidation, a successful check means that the threat is presented as real. I won't tell the players that they think the orc is scary. I will tell them that so far as they can make out, this orc is an unusually powerful member of its polity and has backup very near by. Whether or not that is true, that is how it is presented.
One problem with this approach is that every social skill might then be seen as deception. That might be disambiguated by each skill having distinct requirements, results, and possible downsides. For example:
- Persuasion needs something they want. Persuaded creatures act freely and usually in good faith (they may have their own agenda). They seldom feel umbrage if the attempt fails.
- Intimidation needs something they fear. Intimidated creatures do exactly as you demand, while seeking opportunities to escape or undermine you.
- Deception needs false promises or threats. Tricked creatures behave according to your approach (i.e., persuaded, or intimidated). They are frequently hostile if they discover the truth.
- Performance needs props or devices, and is used to attract, distract, or imitate. If seen through, common reactions are repulsion or expulsion.
So to contrast persuading with intimidating, a successful check makes it clear that the orc will step away from the watch post if given 10gp or the bolt of colourful fabric they were hoping to procure for that price. It doesn't force the orc to step away, so it could be that the outcome of a successful check is to learn that there really isn't anything that could persuade this orc to shirk their duty.