But that's fine. In your game you're indifferent between the two options. Hussar and I are not. All that means is that either you don't GM for (or play under) me or Hussar; or, if you do end up doing that, you change your style, to have more regard to situation (a piece of the fiction where there are dramatic stakes in which the players are invested independently of the fact that, in game, the situation is an obstacle to the PCs) and less regard to the simple ingame aspect of something being an obstacle or not."We need to get into the city, and that requires getting through the desert" is not as different from "We need to get into the city, and that requires getting through the seige" to al of us as it is to you and Hussar.
OK. That's not what I had in mind when I used the phrase, though. And of course there is backstory - it's just that the backstory is introduced in support of metagame goals. The GM needs an NPC to do XYZ, or underpin ABC; so introduces one; and then gives it the appopriate backstory.I interpret "crazy wizard did this" as "some lunatic set this up for no discrenable motive", not as "this location has a rich backstory which explains where it came from and why it is here".
The second bit is the bit where we apply different techniques. For instance, the PCs in my game killed a lich a few sessions ago. Now it's going to come back to have a second go, having reconstituted itself around its phylactery. At the time they killed it, I didn't know where it's phylactery was. I've now decided how I want to handle that (although my players haven't learned that particular bit of backstory is). In making that decision I also added a bit more backstory to the lich, which I anticipate will come out in the pending encounter. But given that all of this stuff is pre-play, it is all subject to real-time variation and elaboration in the course of play, including adding in different backstory if I think of something at the time that will be more interesting and put more pressure on the players.Do we create advesaries? Absolutely. Do I look to the PC's actions and activities and assess what they might lead those now established NPC's to do? Again, absolutely.
I have no idea if Kas would negotiate or not. There's nothing in his backstory that I know of that points either way. (Other than the fact that he is known as a traitor, so may not stick to the upshots of negotiation.) I made decisions about his personality and motivations - including his attitude to the PCs, and to the niece - during play as seemed appropriate to keep the game moving and give the players something interesting to engage with in the situation.As an example, you introduced Kas to your own game because he was linked to Vecna, and there was an existing link to the characters. Did his personality change radically to suit your PC's? Did you create a character from whole cloth to introduce as an "enemy of my enemy" character? Or did you take a pre-existing character whose personality and backstory dovetailed nicely with the PC's activities and backstories, assess the action he would reasonably take based on his established character (and, I stress, only established in backstory, not in play, as he had yet to meet the PC's) and play out the results of his actions? It seems like the last