And to add onto delphonsos questions: can befriending night trolls and other creatures and giving them titles lead to becoming playable races in post world gen or is that too much to ask for?
I would be testing these things but I've got kids and not as much time as i used to.
ok so from what I gone through befriending night trolls currently has a set up of getting them to migrate to the fort... otherwise while it's possible to talk one into being friends the rep of being a dangerous beast to them would override any progress made.
sadly currently there's no good way to make them a playable adv mode species due to the systems that make that work is tied to civs getting access to the creature population and that seems to be not connected to individuals migrating to the fort.
at best you could migrate individual folks into being fort mode citizens but adv mode wise the only vanilla way would be to activate quantum leap through dying and getting resurrected and hope to hop into the body of one of the beings you want to play as... and even then you can't even fast travel or rest or sleep or wait as doing so would kick you out of the body.
though mod wise animal entity tokens does make this possible to play as those creatures and make them citizens.
though playable fiends in adventure mode might require like a setting where a non playable dwarf fort digs too deep and having a player fort ready to conquer the army of 200+ fiends at that exact moment it happens else you just conquer a goblin civ and get access to goblins.
Does that de-escalate combat? Can I give a minotaur a pet bull and get him to like...chill the fuck out?
ok so giving a minotaur or any currently hostile creature a pet would require them to not see you to deeply hate your gift who also alive and can probably be aggro to them, otherwise gifting them a pet could just cause them to hate you more.
as it's the other option on accepting the pet.
so far de-escalating combat for other folks who don't apply an negative rep to the adventurer on sight can be done through series of trinket giving and jokes one could possibly win over loyalty of a patrolling goblin in that when you see them again they will switch sides and help you in an ambush.
that said this does mean you need to avoid getting the intruder rep at all costs, also if the minotaur in this example ended up being the leader of the squad you're assign to then the minotaur would consider you as a comrade and avoid aggression to you as you're an underling.
but peasants will be open to attack as the de-aggro only stops at folks that are enlisted to work for the minotaur and not the citizens of the civ.
so like the process of making them friendly seem to be tied to fort mode migrant function and them arriving to the player site,
so like maybe something that would refresh the nemesis on the historical figure so that they get a new unit that isn't aggro all the time and this could lead to them being friendly, though this would require testing on how the game deals with unit storage to flush the old hostile data and replace it with non-hostile data.