Every randomized NPC in a faction gets added up & divided by 51 to determine their influence (non-procgen NPCs, like Daud, have a preset amount). Every NPC that you get on good terms with in that faction gives you a permanent bonus equaling their influence to your relations with that faction, as long as your relations with that NPC stay good. If you get on the good side of every random NPC in a faction then that faction will literally become incapable of being hostile to you (assuming you don't attack that NPC enough to put you out of that NPC's good graces), with it being much easier if you get on the good side of non-random NPCs who have much higher influence in their factions, with how much influence faction leaders have correlating roughly to how centralized their faction is -- befriending the diktat of Sindria probably would singlehandedly make that faction almost not willing to go hostile with you, whereas the leaders of the Persean League give far less each
