Strong possibility, that world has magic and he was able to create an artificial child, so why not an artificial body as a fail safe in case Claud killed him before he could harness the experiment's (Jennette's) power?
The black haired guy is jennettes Father
I would call him creator, the girl is artificial (made of magic) which I guess would make him the previous emperor (claude's brother).
SPOILER
in some of the latest raws it seems like the black haired dude did something to an item that Jenette was buying (I think for claude?) And it seems to be driving him a bit mad. Could explain why in the book he so easily accepted a child that he knew for a fact wasn't his (the girl was created to take him down). Eventually something would be done to the emperor and Jenette would be next in line for the crown, an easily manipulated puppet.
Am i the only one thinking that the black haired guy next to the duke is the former crowned prince?Especially when athy said his eyes looked like jewels.