tl:dr - popularity of RP suggest more easy NPC motivator/goal generators would be handy.
The various polls that say that for ~50% of people, their
favourite pillar of TTRPGS is roleplaying, ~33% is exploration / problem-solving and ~17% is combat imply that the arguments we hear about systems and editions of games are overly focused on their combat systems.
From this great list of "
Ten Challenges I Love in Games" only 2 of 10 options are combat - 1 is fighting, 1 is evading. 3 are variations on cold 'problem-solving' which the players not their character need to solve and 5 are role-playing - more or less matching to survey responses.
The question I would pull out of this is what sources can we lean on to meet this apparent large chunk of the game? D&D carries a great deal of combat system with it - it did grow out of wargames after all. While 5e DMG has NPC ideals, bonds and flaws (pp90-91) and schemes and methods for villains (pp94-95) these are a little light for people who do not want to conquer the world. I like the
NPC motivations dice-drop sheet from Rolang or you get 'instincts' and 'obligations' from this
NPC generator tool.
My personal approach is to quickly get RP hooks for NPCs is to tag them to their daily activities if there is no over-riding plot hook and then use a factional or
'fronts' style approach. So I will know what 'petty nobles of the Duchy' or 'major craft guilds' or 'good-aligned temples' are generally doing and what this front thinks of various things so these can be subbed in for any given NPC. The party goals table in 5e DMG pp72-73 can be used to generate faction goals though these may be far removed from the aims of an individual NPC. If the minor nobility has a goal of 'hunting a specific monster' then perhaps it will be the topic of conversation at a ball or the obsession over who killed the larges one last season rather than a thing they are all actively doing just now. Once you have that hook, pp244-245 of 5e DMG has a framework for Social interaction assuming everyone starts at indifferent unless there is reason to say otherwise.
Personally I like the 5 steps of the old 3.5e NPC attitudes (pp72 in the 3.5e PHB) which adds unfriendly (between hostile and indifferent) and helpful above friendly. Particularly where weight is being put on role-play and potentially achieving goals without combat, I think this is a helpful increase in granularity. The table has detail but generally DC 15 for Charisma/Diplomacy can bump attitude a step, DC 25 to bump it two steps. The actions that correspond to the attitudes are a neat cheat sheet to help manage face to face encounters without having to think too much on 'what would this NPC be willing to do at this point'.
The other two dials I tend to use is a) how informed the NPC is so whether what they know is close to reality or filtered through fourth-hand tavern talk and b) how much they care about what is going on which will manifest as how intensely they react to things; will they argue their factions point or just shrug and ignore if someone tries to needle them. I have not formalised this as a table, but I tend to block is as a d20 with 1-5 as 'low' 6-15 as 'medium' and 16-20 as 'high' whether that is information or engagement.
Going deeper on all this, I think sources from writing that discuss personality conflicts could be a useful addition to reading lists as sources to loot for NPC drivers and motivations.
