Since Dedue's family comes from a village of blacksmiths, they probably lived near Sacred Gwenhwyfar and the other mountains leading into Fódlan proper.
It's likely that some members of the community were familiar with the basics of Fódlan language, given the mineral wealth of Duscur being its primary interest to the nearby kingdom. Dedue may well have had an easier start than Petra, though he speaks the truth when he says he is stronger with spoken Fódlan than written. Partial immersion upbringing. Maybe he always had an idea of representing the culture of his people to the wider continent.
I actually headcanon that his mother comes from an agricultural town northwards— and that in a different future, he might have left the place of his birth to worship the god of earth in another way than his father, alongside his maternal grandparents.
Other worldbuilding thoughts on Duscur I might eventually move to their own post:
I also headcanon that Duscur was formerly closer to Albinea, and the Sacred Gwenhwyfar mountain range was formed when the geologic plate slid into Fódlan's continental plate. (This would be related to my ideas on trade with Albinea, local ecology of northern Fódlan, and extant relict populations of elk descended from Albinean domestic reindeer. The berries are like salmonberries or gooseberries.) (Alternatively, Albinea broke away from Fódlan and is moving north on a tectonic scale.)
There's probably also long tradition of smoked, pickled, and salted fish, considering the peninsular marine access and nearby salt mines in the mountains bordering Pryderi territory (latter info from Hopes). It's said that Duscur has rich forests, implying that wood (likely larch and bristlecone pine) is not a popular building material for typical domiciles or water vehicles. The flowers of Duscur in Garreg Mach's greenhouse are drought resistant, but easily overwatered by the freshwater available for that purpose, possibly indicating a brackish origin with halitic soils and saline water table. Seals are abundant along the coasts of rocky cliffs, similar to in the real-world northern United Kingdom. Perhaps selkie folklore can also be found in Duscur. Sealskin is probably the boatbuilding material of choice.
We know that Duscur culture also has a bear totem; this could be like real-world Korea's, or Siberian and Inuit, origin myth cosmologies. Bear meat is sacred to the Ainu of Hokkaido and Kamchatka, consumed ritually as part of ceremonies honoring the relationship local people have with the land as participants of a cycle both spiritual and ecological. It is likely that Duscur bears are closest to the Eurasian brown bear. (I have a special place in my heart thinking of it as the Ussuri subspecies!) Due to the presence of bears, wolves have less prey and territory for hunting and a lower population in the region.
With mountains, coasts, and bears, we can assume Duscur to have an annual salmon run and plenty of rocky postglacial waterfalls. Add that to the tourism bureau's pamphlet right up there with the wildflowers— I prefer to picture something like bluebell woods, personally.
The Duscur people have probably domesticated some sort of gourds, like calabash or pumpkin or acorn squash. Root vegetables may be more common than leafy greens, depending again on soil salinity.
Something many may not have considered before is the presence of beavers in Duscur. Beavers are an excellent way to decenter European ecology and culture from wider historically inspired fantasy works, since they went nearly extinct in that region just before the Colonial Age. The second largest kind of rodent, and the largest endemic to our planet's northern hemisphere, beavers are what are referred to as 'keystone species' and 'ecosystem engineers'. A really effective way of representing the negative effects of imperialistic colonization is through the degradation of local ecology as beaver populations decline from fur hunting. Using the beaver as a symbol, we can represent a shorthand for the reintroduction, reconstruction, reparation, and respect for indigeneity promised by King Dimitri Blaiddyd I of United Fódlan to the native Duscur people.
A fantasy setting offers fascinating opportunities to think about what defines something in our world and to look at how it might be different with different physics. What if beavers had gills? What if otters could transition from sea to river? What if seal blubber had flavor? What if flowers were salt-tolerant!? I really enjoy exploring potential answers to the questions Fuukasetsugusu doesn't even realize it asks, and I hope my posts can get some readers experimenting with what the more mundane aspects of fantasy world might look like.
