I’ve noticed that most GMs seem to lack tools that can fill the gap between “charisma roll” and “play the persuasion out” and give some structure to the latter. Here is a possible solution.
This is obviously not a perfectly realistic system. I’m not going to quote Cialdini in here, just provide a loose framework.
The paths into a character’s mind. It’s good for the GM to have an idea of them for the important characters.
You need to figure these keys out for a given character, preferably in a manner that won’t make it obvious to the character, and give a good impression that they can address them.
What is the most important thing to them?
This is usually an abstract concept.
A character who values their nation over riches won’t be easily bought, but they could be manipulated with jingoistic arguments. Likewise a character that values power or gold won’t be moved by valorous speeches.
This implies a hierarchy of values that can be constructed more thoroughly for main characters and just hinted at for minor characters. For example, a character can value riches, but they might put that aside to protect their family.
Examples of this are: Power, Influence, Riches, Family, Nation, Ideology, God, Pleasure, etc.
What do they want?
This is more immediate, actionable, usually directly stemming from what’s important to them (in point 1).
Family - I want my son to become a cavalier.
Riches - I want my business to succeed.
Pleasure - I want money to feed my addiction.
In order to successfully persuade someone, offer them something they desire. It has to be demonstrable that you can do it.
For example, if you’re established as a captain or an inquisitor, you can offer to recommend the character’s son for a promotion in the army. It’s provable that you can do it (you just need to show the badge).
People won’t always give you a straightforward answer as to what they desire. Study them closely, ask the right questions, figure out what makes them tick.
You don’t need to do everything verbally. If the person you’re persuading is interested in Riches, shaking a jiggling sack and a mention of pay in your request may be persuasion enough.
What do they hold dear?
This is something tangible (unlike 1. which can be abstract) that they have and want to keep.
In order to intimidate them, threaten to take it away in a provable fashion.
Holding a member of someone’s family hostage is an extreme example of this. You can also show an inquisitor’s badge and mention interrogation (implying taking away their health or social standing) or wave an order from the governor (imply taking away their business or causing other trouble).
For deception, another layer is added: how likely are they to notice that you’re lying?
Here, you are weighing the things that match versus the things that don’t, that they’re likely to notice.
For example, when trying to pose as a guard, ask first: are you trying to pose as someone specific before someone from their life, or just another guard? If you can appear semi-trained to another guard and are dressed in a uniform, there is little reason to believe you are anything but.
Issues might arise in specific patrols in elite groups where guards know each other’s names, silhouettes, style of movement, etc. Similar problems show up when you’re trying to pose as someone you’re not before their family member.
My policy for this is “So long as they don’t have a good reason to doubt you and you have some skill in deception, you’re fine”.
For the purpose of seduction, the factors that come into play (i.e. what they desire) may include: body type, personality type and sometimes assets such as riches or noble birth.
Take into account that a character may have different requirements for a one night stand versus a prolonged relationship.