If I recall correctly, Roy was only 50% Kai. Either way, he was exceptionally intelligent for his race. Also, his father (I think?) Thorne or something, the leader of their area, educated him very well. I think he intended to use this marriage to his advantage and pushed for it.
Around 60+ chapters. The higher civilization took notice of them (ML beating the zerg queen, his recovery, and the sudden 4 children) and finally came to their planet. I kinda like the duke (the representative). He and his kind were like grey characters. Apparently, this higher civilization was the one who helped humans to adapt after the immigration that happened. They gave their genes to the human to mix, which cause them to have their abilities (as explained early in the story). Of course, there is no free lunch in the world. They did this because as their power advances, they lack the ability to give birth. Although they lived longer, their populace was shrinking. And at this point, most of them are elderly. They hope that humans, who acted as their now guineapigs, would be able to find a breakthrough once humans face the same problem. Which the MC did. I'm very satisfied with the duke's characterization. It makes them human. He calculates the MC and ML, like wanting their genes and to do experiments on them, also wanting to strike a deal but not wanting to fully give away his civilization's technology. He lacks normal morals in certain parts (wanting to marry MC because of his ability to give birth to 4 at once, regardless of MC being married) but this is only because his race has different priorities XD. Despite all this, the duke has a bottom line. -he wanted to see the 4 children. This scared the ML and MC thinking he wanted to experiment them. The duke wanted to experiment on the leads but not the children. At most maybe study how they are reproduced. On their planet, babies are rare and it was normal for people to visit other people's homes once they give birth to see the newborn. In this case, the duke was thick faced. -There's this guy Gerald(?) who eaten the pregnancy dan and now pregnant with twins. He was hiding it because 1) he's a man 2) the other father is Fang who he has a hate relationship with but now pursuing him after the one nightstand. The duke's device was equipped with a sensor that alerts him when there is a pregnant woman around. It can also scan the status of both child and mother. All of his kind was equipped with this in case of an emergency. There was this accident that happened to a pregnant woman and wasn't able to receive immediate attention because they did not know she was pregnant. (They'll make good husbands) -So the duke detected that there's a pregnant woman with twins. He was elated, thought Gerald was a woman and if Gerald was not pregnant, he will marry him (lol the last bit of his morals). Now Gerald's pregnancy got public because duke cannot contain his excitement and people were shocked because he is a man! ML took advantage to bring out the existence of pregnancy dan and throw the cause of MC's pregnancy to the medicine as well. (The Zhou said that MC was not a kay so people are wondering how he got pregnant). -The Duke got more excited knowing such medicine existed and accidentally release his ability's pressure. He immediately retracted it saying to himself that there's a pregnant woman beside him so he cannot be careless. -He went to ML house, detected that ML's mother is currently pregnant with his device. ML's mom was speechless. She was waiting to hug her grandson but now she was pregnant with her own child?! She went back to the house and end up running. The duke was shouting like 'pregnant woman should not run!!!' -the duke looks down on MC because he has no ability but will still act properly because MC can be pregnant. (Oh their priorities XD) -So he went to see the eggs. Once the incubator opened up, all of them jump out and into their parents. Poor duke had the heart attack of his life. Panicking, 'Be careful!!' 'This is a precious child' 'how could you just grab it' -Seeing the healthy children, the duke's heart melted. But seeing such scene, he was anxious and was panicking. He wanted to teach MC a thing or two (beat him XD) but MC was holding the children so he can't. So he proceeds to have parenting talk with MC (lol) and even wanted to demonstrate how to hold the children. The duke educates the MC that he cannot just leave the children in the incubator and that it was not good for the children's mental health. MC now likes him because 'You know a lot!' -Duke was very proud to say that he got full marks on his pregnancy course ahahaha. Apparently, everyone in his race needs to take the course. He's like an anxious, panicky, distressed uncle that I laugh at him. But he's scary as well. He was stronger than ML and their race was a few lvl stronger than ML's. For them, S lvl were not that rare. Also, he seriously reports everything back to their planet. From the start their goal was clear. Thankfully, although they indeed thought of forcefully getting ML and MC, they were not brainless cannon fodders and thought to negotiate peacefully first.