I've seen it in one of the comments in the novel, but I think it wouldn't make sense to apply human morals on a literal dragon. Karas is literally mostly a dragon by nature (if not completely) and his upbringing is shitty. I'm not one to justify his killings, but do we get this disappointed on wild animals when they kill without reason? I think it would be easier to swallow if we'll stop seeing him as a human being (cuz he's not)
Plus it was clearly stated in the novel that Karas is very child-like, and he didn't kill the King's Heart immediately cuz it's not fun for him. If you're to stop overthinking his actions, you'll see that his intentions are very straightforward. Just like a child's, it is solely focused on what he enjoys. He's still very much stuck in his lost childhood cuz Abel dies way too early, and no adult was there for him to trust enough to guide him emotionally (not even Ashler)
Anw, my point is js this story wouldn't stand out amongst others if Karas will be all lovey dovey after being literally tortured since birth up until now. I do believe (and hope) that Abel would be able to make him feel things, but it would make so much sense if he did not. He's a literal predator, a freakin dragon. Let's not forget that he's still a victim (of the King's Heart), through and through.
At first I also thought about considering the fact that King Karas grew up in an abusive environment and is of mixed race. However, even animals have more empathy than him, when it comes to their group or species. And children tend to gain sympathy when treated well. He simply doesn't have any of those attributes. If we're being honest, he looks more like a noble medieval psychopath. I stopped being able to enjoy his "cute moments" with Abel.
I sincerely hope that the webtoon adaptation does not strictly follow the novel.
I had to stop reading the novel because I couldn't swallow King Kara's cruelty. He kills innocent people for such trivial reasons and the most annoying thing is seeing how easy it is for Abel to overlook this, demonstrating a surreal understanding.
Which ends up not making much sense to me about the author's logic, because if it is so easy to kill, why not annihilate once and for all the members of the king's heart?
Anyway, the story has a good premise, but in my point of view, it wasn't explored in the best way possible.