Quote Originally Posted by Naria View Post
To be fair, bastard surnames are an actual tradition that GRRM just expanded on. The illegitimate children of English royals were sometimes called Fitzroy or "son of the king". But yeah, this is definitely invoking GRRM's works.
Yes, I think it is Game of Thrones thing. In England Fitz was used for bastards (not only royal), life Fitz James Stuart are from a bastard of King James of England and Scotland.

But I think usually if the father recognised the son (all Europe), he got the family name but no inheriting rights. (Fathers usually took care that their bastards did well too. Kings gave titles and lands or managed church positions, other important fathers too. Popes, cardinals, bishops etc also had bastards and took care of them, usually with their father family name.)

If there is no known father the son would normally have the mother's family name.

And when no father nor mother is known, they might receive some surname indicating that origin (such as Exposito in Spain) or just give the child a frequent family name. That idea that all bastards of some region or kingdom are given the same surname is Game of Thrones mostly.