@Voidreader01 it's to do with the fuedal system
Example
Main family/ family of the son/s that inherited the patriarch position
"John (Von, De, el, ect. Will go with von here) Smith"
Family of sons who don't become patriarch, aka branch families
"Jack Smith"
Some feudal systems used the existence of the middle name as the sign of nobility, that's why in some stories the mc will be ceremonial given a middle name by a king to show their status, or in cases like reincarnated as the 8th son, the mcs older brother gets to keep his middle name when he becomes patriarch, and later when the mc gets recognized for his actions, the king says his name with his own new middle to show even though he's from his family, he's his own noble, other stories even use the middle name to show who's the mothers of the family members as usually in these stories characters don't have the same mother's, only the same father's, which is the case for this story even.
Example
Main family/ family of the son/s that inherited the patriarch position
"John (Von, De, el, ect. Will go with von here) Smith"
Family of sons who don't become patriarch, aka branch families
"Jack Smith"
Some feudal systems used the existence of the middle name as the sign of nobility, that's why in some stories the mc will be ceremonial given a middle name by a king to show their status, or in cases like reincarnated as the 8th son, the mcs older brother gets to keep his middle name when he becomes patriarch, and later when the mc gets recognized for his actions, the king says his name with his own new middle to show even though he's from his family, he's his own noble, other stories even use the middle name to show who's the mothers of the family members as usually in these stories characters don't have the same mother's, only the same father's, which is the case for this story even.
Life is like lemons, I hate lemons.