I’ll just preface this with something from the Q & A:
Whether or not animals are restricted to these two classes I’m not sure, but that would make sense.
However I do like the idea of a relationship between an animal and the settlers, but I think these things would have to be restricted to class - you shouldn’t have your bog standard villager best friends with a dragon, he has to make do with cats and dogs and the like.
As for military units then I am primarily thinking Game of Thrones Direwolf style.
But yer, there’d have to be some sort of restrictions depending on the purpose of the settler, perhaps each class would have one or two animals that they can form bonds with, civilians only able to form relationships with passive animals, and military units with offensive animals.
The benefits of such would probably be something along the lines of buffs/debuffs or certain benefits - so the farmer who has a favourite cow gets more milk. The archer who has a favourite eagle can see further. Obviously this is me just chucking random ideas out there, but I’m sure you get the picture!