@bear_necessities said in Difference between an NPC and a Staff PC?:
Counterpoint: why would you use NPCs in the last situation? This could be easily accomplished and provide a better story for PCs to have the "master assassin" charge a lower level PC assassin to do this in order to prove themselves or move up in assassin society? Now you are providing story for multiple PCs and not making your npc a pivotal part of the story.
On some games, that's absolutely the right choice! It depends on game culture and circumstance. And I can come up with other examples than the assassin one, as well, for different game settings/cultures. There's no absolute example that works in every setting and every game circumstance; even your counterpoint to this specific example doesn't work for every game setting and culture.
Maybe the game has player secrets; there's a PC assassin, sure, but if they target another PC, even if the PC dies the player maybe tells people afterwards. Now people OOCly know that character is an assassin and find things to "notice" ICly and become suspicious. ("Gosh, Jane wears a lot of dark clothing and has a bunch of large rings. You know who else I've heard rumors likes that style? Assassins.")
In some game cultures, open PvP where another PC opposes (or kills) your character leads to all kinds of OOC drama; maybe everyone OOCly knows Jane is an assassin and that's fine, but you don't want Jane dealing with OOC shit on channels over this. Whereas if this thing was done to you by an NPC during plot, it can feel more like "story" and less like "Jane, who I still see sitting on channel and chatting happily, did this to me, the bitch. My next alt will be written with intent to destroy her."
Maybe you just don't have any PC assassins played, and there just isn't a PC to task with that. Maybe you have only one PC assassin, and they say they're OOCly not comfortable with the task because they're afraid of that possible OOC blowback from the target PC's player and friends. It doesn't even matter if that fear is justified; the target could be the nicest player ever OOCly, but the assassin player is carrying around trauma from a previous game where their life was made OOCly miserable after they did something IC to derail another's plans. (And I'd argue that if you force a player to play out something they are actively OOCly uncomfortable with even after being told of that discomfort, you're now doing GMing wrong.)
My point here wasn't "this specific example always justifies an NPC sleeping with a PC, and therefore NPCs sleeping with PCs is okay", which would be a tough argument to make with any example, but rather "I think saying an NPC sleeping with a PC can never serve story is not accurate; I can see places where it can serve story, so I'm not comfortable making such a blanket statement".