My friends and I have been playing DnD 5e for a few years now, but now I’ve decided to start GMing PathFinder 2e. We’ve played through most of the Beginner Box, and now I want to continue with my own homebrew content. As part of my world, I want to introduce a fighter “subclass” (probably the wrong terminology for PathFinder). What I want is a tribe of warriors who fight without armor (starting at level 2 or 3), and to compensate for the lower AC they get magical tattoos which increase their AC. It will also be possible (when you advance in levels) to choose to add other tattoos with other magical effects.
So my question is: Is this what archetypes are for? Because I don’t think “subclasses” are a thing in PathFinder? Or how would I go about this?
As far as I understand it, archetypes are more of Pf2e's way to do 'multiclassing', where you choose feats from an archetype instead of your normal class feats.
So you're right, there is no direct correspondent to DnDs subclasses in PF2e. But many classes still have subclass-like specializations. They have different names for each class, for example 'ways' for the gunslinger, 'instincts' for the barbarian or 'arcane theses' for the wizard. These in themselves tend to have a little less meat than 5e subclasses, because you still have a lot more customization options with your feats. Mostly they modify a core element of the class and also give acess to specific class feats.
Sadly, the fighter seems to be be the odd one out and is designed to not have any such specializations. Maybe so it can be a beginner friendly class that doesn't overwhelm the player with choices..?
So as I see it you might:
a. just make some appropriate fighter feats for your culture that any fighter can choose (with whatever restrictions you place on that as the GM, regarding backstory, etc.). This would be the easiest in my eyes, as you could orient yourself on existing feats for how much these should be able to do.
b. you could make this an ancestry/heritage thing, seeing that it should be tied to a culture. Maybe not exactly what you want, if it is supposed to be for fighters only. Could work as just a generally available ancestry feat/series of feats that players can choose. However these often don't make mayor changes to a character and rather give a small bonus to something.
c. make a new class that gets all the same stuff as a fighter, except for some things you replace with your own homebrew. This might get a bit more complicated than creating additional feats.
d. figure out how to modify the entire fighter class to offer a subclass-like choice. I wouldn't know where to start on this one. This would easily break something in how the game is balanced and feels like a job for people who are on a level of understanding this game on par with the designers at paizo.
Just as a final note: I haven't really started to homebrew much in PF2e myself, so my ideas on this might not be super accurate.
Archetypes are an interesting beast. They are the primary pathway in the game to taking on feats and features from other classes, via Multiclass Archetypes, but they're a lot more than that, too.
One of the things they're leveraged for is class variants. There's not a wealth of examples in this category, but it's kind of tantalizing. This is where you find PF2's equivalent of the Wild Mage, the Wellspring Mage. It's also where you can straight up just choose 5e style hybrid casting, with Flexible Spellcasting.
But the real core of Archetypes seems to be turning background flavour into defined game mechanics. Here, OP could make a melee archetype that could apply to the Fighter, Barbarian, and Monk classes, providing depth of fighting style and role to this society without needing to develop independent subclasses for each of them.
It's closer to the way D&D 4e did multiclassing. 5e-style multiclassing simply isn't possible in PF2.
But yeah, "multiclass archetypes" are the closest you can get in PF2 to multiclassing. Other non-multiclass archetypes exist too, and these are most similar to D&D 5e's "prestige classes", which exist only in the form of a single Unearthed Arcana (the "Rune Mage") and a few homebrews (Walrock Homebrew's "Vampire" prestige class was especially good). Basically: it's things where you get too many different abilities and have some kind of progression, so it's too much for a simple feat, spell, etc., but not enough for a full class, and probably not something you should be at level 1.
Just noticed from the other comments that my option a is just the same as an archetype without the archetype part... so yea, still have to get used to how PF handles these things myself 😅