Ok, author-nim I think you got things mixed up, the child is suposed to be unable to contr...

I know you're joking around and being sarcastic, but there are plenty of "grown ass" adults that I've had the unfortunate pleasure of meeting that were extremely emotionally immature. Just because someone is grown up on the outside, that does not mean s/he is grown up on the inside (in terms of EQ; meaning Emotional Quotient).

I agree, however Ain and the Duke are father and son, and the Duke was Ain's only guardian/ parental figure until recenty. We know the Duke has low EQ, so here is my question... How the heck did Ain learn how to read and control people's feelings this well? If a skill comes from nature, nurture or something you learn later on none of those can be aplied to only Ain and not the Duke.
His dad has low EQ only gives the example on how to make people fear you, not like you. and is obviously older , how can Ain be that much of a manipulator and the Duke that much of a block of wood?
I know it's just major nippicking and my general dislike for the child possessive yandere manipulator level1000 trope, but it really doesn't make sense

I wouldn't call it nitpicking at all. I think that in manga many child characters seem somehow "wrong". Like this adult in childs body character or some cute kid who's only personality trait is being cute. I'm sure it's not easy to write a child but was the Author here even trying ^^

I think the point of writing Ain's character as it is currently was not to portray a "cute kid," but to portray the evil side of Ain that is manipulative and cruel. It was stated in the earliest chapters that Ain was the villain in the story our MC was transmigrated inside, and even that Ain's father was an even worse villain.

The huge factor in all of this is the way the father and son combo were raised. It was stated by the nanny that the family is supposed to have no "weaknesses," which even includes allergies. Imagine how much psychological damage being raised that way would affect the mental state of a child and then later as an adult. That often has a huge effect on EQ, which makes weaker mental states even more susceptible to bad coping mechanisms.

We see the emergence of a lower EQ with Ain's father due to the sudden strangeness of our MC, making him feel things he's probably never experienced before; like jealousy, for example. It's making him act out in ways that a child would, like having a tantrum. He likely never experienced a proper childhood, thus his childish reactions are due to his inability to mentally mature. And I'm assuming that is exactly the case for his son, Ain, as well. But instead of behaving childishly, Ain is doing the exact opposite. Not because he is mentally mature, but rather it's a coping mechanism of sorts to handle all of the past trauma and the pressure he currently endures as his father's heir. And with his mother, our MC, he's starting to relax around her, making him crave a mother's warmth, love, and affection—something he never had before. So it's making him that much more desperate to keep her at his side. That was shown in one of the more recent chapters with Ain ordering the servants to treat his mother nicely and even with Ain telling his father that he didn't want his mother to run away.

So Ain's father isn't a "block of wood" and Ain himself doesn't have a weird character design. It's simply based on perception. But these are my personal opinions from what I've gathered as I read the story, so please don't attack me.

huuuh interesting.... Since we only have very few chapters to reference it seems plausible as well. If properly done it would become a favorite. Very good analisis! it's a point of view I would take a while to consider( if ever)

@CuddleQuill Never gonna atack you for having a diferent opinion, I kinda love having discussions so diferent opinios are always welcome