@botodopo
Well the boy unknowingly proposed to his mother and she accepted so to think his gramps was out banging cats doesn't surprise me all that much
Not to spoil anything, FYI, origin of cat princess will be explained later, at least it's explained in the novel.
Just to clear some confusion/assumption, feel free to read the spoiler:
It's actually about "ancestral bloodline manifestation" (IDK the correct translated term that means 返祖現象, maybe atavism?) that passed down in their royal genes. Olivia is not a human too due to the same reason... Ain's identity is even more complicated and only a half-human that's not even birthed through human's reproductive method but that's another thing already, which if things go on like what the story and dialogues are implying in the story, actually makes his possible relationship development with his mom more complicated and potentially problematic/controversial for some readers despite it's in a fantasy world.
Basically, in their fantasy setting, some humans might revert back to the species that some of their ancestors were. So technically, Kadyma the 1st princess isn't a "half-cat" offspring of a human and a cat, but a beastfolk/beastkin/beastman, or maybe a human with ancestral's species abilities and physical appearance, it's not explained in-depth yet up to the point at where I read in the novel.
The Duke broke a agreement, loses his country a market and possibly made a big country his enemy and of his own country... The Duke is a stupid! If I were the ruler of his country I would kill him on the spot and send his head to the other king to beg for forgiveness.
@Karmichel : Earl not duke, and if the country was run by intelligent people he would have been punished as soon as he started treating a foreign princess as a servant, and not been allowed to chose the 2nd son as his heir, or spread slanderous rumors about his 1st born (you can see the other nobles talking about how Ain has a bad temperment at one point, which is weird since no one has ever interacted with him, so it must have been planted by them).
but they will only give him a effective slap on the wrist with a demotion and loss of territory, due to his past accomplishments, and they do not ant to lose the 2nd son's skill. They are idiots only concerned with the skil someone was born with, even though they do not understand all them (the grandma decided ain's skill must be the same as the more common skill with a similar name and never considered what skills he might develop, the knight Chris has at least one high tier skill that is from training and job development, not what she was born with, and Ain had already developed a new skill when Olivia gave him the status card), and the bullies of their continent.
@suzubelle : Olivia's family are more educated. Though from what I got from MTLing the web novel, I think they saw his skill before, and realize how valuable it is, or at least have the brain power to realize "unknown = very rare, and rarity is a strong indicator of value when applied right" unlike a certain other family.