@bear_necessities said in Difference between an NPC and a Staff PC?:
This isnt a pearl clutch. I will just never understand why staff feels the need to utilize their NPCs to have "romantic plot" or bring a child into the world or fuck somebody (which again, does that benefit the game or at least a certain group of PCs? Because it sounds like it benefits 2. The PC you are boning and the NPC).
So, let's say you're in a modern setting but where a lot of the conspiracies around secret societies are real. The Illuminati, the Templars, and so on. And there's an NPC, a senator who is a mid-level member of the Illuminati. And he'll do favors for the PCs, pull strings to get them resources, but he always asks things in return. And owing him open-ended favors is... unsettling, because sometimes when he calls them in, the people who are called come back subtly different.
Now, here's your character, who needs a piece of information they know that NPC has. The price, however, will be too high. So your PC decides to seduce the NPC senator. Maybe this is because they think if they succeed, the NPC will feel more inclined to do them a favor without demanding one in return. Maybe this is because they think if the NPC takes them back to a hotel room, they'll be able to take his phone while he's asleep, use his fingerprint to unlock it, and get the information for free.
Either way, this is a situation where the PC seeking romance/sex with the NPC serves the story; the PC can gain something which advances their storyline. If they were trying to get that information for a plot involving multiple people, it advances storyline for multiple PC's!
Or maybe the PC has been pushing something politically which a sinister secret society wants stopped. PC knows they want this, but has refused to be cowed by their demands, to a point that the society has decided to act. The NPC is a master assassin hired by that society, and wants to get close to the PC in order to poison them in private; once poisoned, they can blackmail the PC into doing what they want by withholding the antidote. Try to force them to turn on their allies and serve this society's interests instead. And what better way to get them in private and poison them than to seduce them?
Here's a place where the NPC seeking sex with the PC serves the story.
There honestly are reasons where it can serve story. I'm not saying it always does when people do it, but I think it absolutely can.