This is quite interesting to me.
In Hinamatsuri the manga, it is not revealed that these two characters are father and son.
Or better, the mangaka never tells this in the manga -- he reveals it afterwards, in his final notes.
Here you can see that they took note of this relationship and put it in the anime. I liked this very much -- well done! ^_^
P.S. The son is Sabu サブ, and the father is the guy who's always seen drunk in the Little Song bar.
He actually says 兄貴, "aniki", not "boss"!
I like very much #Noblesse! It's nice to dive again into that beautiful story. What I find strange is that the story takes place in Japan. It's strange, was it so necessary to move the stage from South Korea to Japan?