Yeah Kais and his brother look like Emperor Dad's younger brother, and since there are so many off shoot kids from the previous emperor plus the experiments they were trying to conduct on them at the beginning that seems pretty reasonable. Which might also be part of his extreme reluctance if daddio to have him around.
Umm this might sound mean, but the artist could have "same face syndrome", its not exactly uncommon. It might be because her type looks wise is a bit similar to her dad (I know I know its freaking weird), so he's likely made to be the younger/ more age appropriate version of her type (lol even though she prefers the looks of middle aged men more). Tbh I agree on the uncanny resemblance, but it also might just be a coincidence stemming from the art style.
I thought it was the black hair and purple eyes situation like the Emperor's mother. That and the artist seems to only be drawing people with the black hair and purple or gold eyes in relation to the royal family unless I missed some extras, which I totally could have XD.
Im 10000% kais is related to the ravenhook and abt the whole duke’s approvals things, i think it’ll just be like, the current duke ravenhook will get his downfall and the title will be passed to kasi or smth