Possibly the latter I could use being drunk, I might relax better, as over stressed from work.
I can sympathize with the work issue. Personally, I'm a fan of having an Old Fashioned before bed.
What issue do you have with this?
I don't have an issue. For the record, I am the original 'edition warrior'. I unapologetically advocated against the design choices in 4e from the very start. Based on WotC's hints about where they were going, the lack of transparency, the revocation of the OGL, and their disparaging comments about 3e, I felt from the start that 4e was not going to be the game for me and was too radical of a departure from prior versions of D&D. I called it "D&D for people who have never liked D&D before". It was an appeal not to their base, but to the people outside of their customer base.
But I've never particularly thought it was a bad game, have admired certain things about it, have no problem with its fans loving its positives (the things as this thread says, that you gain compared to Trad D&D), and even took a few queues from it in my house rules - at least to the extent of taking my thinking in some directions I would have never gone without exposure to it.
Likewise, I don't have an issue with how you handle the considerable challenge a DM faces in animating the NPCs in the game. Fiat is a perfectly valid manner of handling NPCs, and all DMs rely heavily on fiat when running NPCs simply because as you said, no table can simulate meaningful conversation or capture the complexities of a character.
What I am asking, for the purpose of provoking discussion, is how different GMs handle the issue of fiat NPC behavior and in particular what NPCs that they handle solely by fiat, and why, and what portions of NPC behavior they handle solely by fiat, and why.
So this gets us done to the only "issue" I have, such as it is, which is I don't think from what you are saying you view an NPCs disposition and his personality as separable things in the way I do. It comes down to what you mean in the following quote by "reaction".
"No "predefined npc" means I have enough information to decide their reaction or actions by roleplaying I do not like the simplistic table results and randomness. DM choice has more nuance and can have more contextual meaning than any table."
So, when I'm running an NPC, any NPC at all, the NPC's personality is not the same thing as their disposition toward the party or the individual members of the party. Their personality is something I decide and animate by fiat, largely because I find it quicker, more interesting, and more realistic to design NPCs in that manner rather than consulting a random table to brainstorm up a personality. I do this because, IMHO, I'm actually a really good NPC designer. And this fiat assigned personality is something that I apply to all NPCs, and by the nature of personality it has to be run by fiat. Game rules can't tell me how an NPC will behave or what an NPC will say. Game rules can't bring depth and life to NPCs.
But that is not at all what I use reaction rolls for. Reaction rolls have nothing to do with a person's personality. Reaction rolls tell me about the NPCs disposition toward the player, which is something that is only partially fiat in my mind. I mean partially fiat because for what you call 'important NPCs' (if I understand the term, more on this later), I usually set the initial disposition of the NPC based on the NPCs personality and his likely disposition toward the party in the circumstances they are likely to encounter that NPC. So, an NPC priest of a charitable deity or one that favors heroic martial action is likely to be favorably inclined toward being charitable, or toward warrior mercenaries that show up in their temple. A kind hearted nobleman known for his hospitality is likely to be favorably inclined to strange visitors. Other characters with different beliefs, goals, and personalities might likely have different initial dispositions. Likely to be, but not necessarily so. You could catch them on a bad day. They might not like your looks. They might make false assumptions about you. They might have a particular prejudice against short dark haired men.
This initial disposition I set partially based on fiat.
But what I tend to do for almost all NPCs, is give the story a chance to go places I didn't expect by giving the PCs a chance to at least partially overrule my fiat. There are a couple of reasons for doing this, but one of the most important is that it means charisma is not a dump stat. For example, there are in my game advantages you can take that make it more likely for you to give a good initial first impression. Conversely, if you are a sorcerer, then there are advantages you can take that often have offsetting social penalties - think mutations that render you outwardly non-human. These tend to cause you to give bad initial impressions. You walk up to someone that might otherwise be hospitable and you have glowing red eyes and horns, they are very much likely to react differently to you than they would if your appearance didn't come as such a shock.
But again, while the disposition is often influenced by fortune and rules, how I play out that disposition is a matter of fiat based on the fact that no table can tell me either how an NPC is likely to reason or what would be fun for the game. If an NPC is hostile, it doesn't necessarily mean that they immediately draw a weapon and suicidal charge a band of infamous mercenaries. It means that they are at the very least unhelpful and do everything in their power to oppose and undermine the target of their hostility. They could assist enemies of the PCs. They could refuse service or charge excessive prices. They could spread slander about the NPCs behind their back, poisoning the disposition of other NPCs. They engage in spiteful acts, arrange ambushes, spy on the PCs, or whatever. In some cases, hostility just might mean that they NPC flees the PC and thereafter attempts to evade any future interaction at all costs. Or in the case of an NPC that is very good at lying, this might mean a very hostile NPC pretends to be quite friendly. So knowing that an NPC is hostile doesn't force tell me how to RP them except in the broadest terms: they act differently than they would if they weren't hostile.
Any NPC, regardless of personality, can be either hostile or helpful (or anywhere in between) - even one that is a charitable pacifist. It has nothing to do with personality.
My question is, do you make this distinction? It appears you either regard personality and disposition as the same thing, or think neither has anything to do with fortune and rules.
However, you seemed to make a caveat with regards to "unimportant" NPCs. So, my question was, "What makes them 'unimportant'?" That term could mean a lot of different things. Do they have low social standing within the imagined society? Are they not expected to play an important role in the narrative? Do they have in game terms little power? Do they have no myth associated with them prior to play? Some combination of the above? Etc.
I ask, because I don't really make this "unimportant" distinction, and to the extent that I did it probably wouldn't be congruent to your meaning. One of the longest most reoccurring NPCs in my game is a 1st level commoner who was detailed in a few sentences as a unknowing minion of an 'important' villain in the story. I had know idea what that characters roll in the story was going to be or what her disposition toward the party would, but that character had a name, a backstory, a motivation, and a personality (in about as many sentences), and as it happened the relation she has to the party is as the unintentional victim of a party member's arson which I decided evolved her into a ghost haunting a party member.
