I'll create a, very short example, completely bogus scenario just to get the point across and hopefully make things easier without spoiling a real one.
Village of PooPoo tier 1-5.
You start with the Venture Captain RP encounter, ask your questions. Roll Geography if you have it. If you get a 20+ you learn that Celestial creatures known as Lillnds have been seen dancing around the woods. They are not a part of the adventure or any encounters. This is merely Geography fluff.
Scenario Encounter 1, Battle. Win it, keep walking through the woods.
--> Insert GMs own personal encounter 2 since the scenario usually wraps up within 2:30 to 3:00 hours.
If the PCs make a DC 13 Perception check: They spot a Lillend hiding and watching their travels (Lillend has no stealth skill so take 10 +3 dex used for basis).
The sole purpose of this encounter is to talk to the PCs and have a little language fun. The Lillend begins speaking Celestial, if no PC understands it she speaks Draconic, If no PC can understand this she'll roll her eyes and use her Truespeak ability to speak with everyone normally. RP happens and the PCs continue with the regular scenario script.
Rest of the scenario encounters, run as per normal.
---------------
The intent is to be merely a little bit of extra RP to enhance the scenario and throw any skilled players (such as those who bought it and never ran it, just so they could know the treasure/monsters) for a little bit of a loop.
It's just RP. There is no fighting or changing any of the scenario monsters or stats.
Here's the problem, the intent is this:
"PFS RP Guild Guide wrote:
GMs may use other Pathfider RPG sources to add flvor to the scenario,...
No matter how innocent someone's intentions are someone has the right to pull this:
"PFS RP Guild Guide wrote:
Scenarios are meant to be run as written, with no addition or subtraction to number of monsters...
They'll run around proclaiming that you added a monster or even that nothing about Truespeak says it can be turned off for the GMs personal fun.
Honestly you always have the chance of -that one player- who justifies someone hiding as a means to immediately attack without repercussions. Naturally being a CR 7 creature in a tier 1-5 it will run and not fight the PCs but... You could end up with that one.
---------
Thoughts on this?
Every done something like it? You know, not just adding a shop in town where a player is less likely to jump and attack the owner.