
Well in their case, the emperor needs to make children for the sole purpose of having them fight each other(i guess it's tradition?). Also, i believe the emperor's little conscience left thinks that it's wrong but he doesn't care since he grew up like that, he needs to do the same with his children.
I'm not justifying nor tolerating their way of doing things tho.

the current emperor didn't do the killing of his siblings, it was the late 1st prince who gathered all the relatives and supporters, like what happened in the red wedding in got. The background story for that was already laid out in the story and earlier chapters. I think this current emperor is just a survivor who didn't plot like the late 1st prince.
Just don't have kids if you're not going to treat them as such, or show interest in one cuz she is acting cute. And that is only because she is an adult in the body of a child so she knows how to curry favour. If you yourself went through shit life as a kid then u can definitely try and not do the same to your kids or if you don't know how to do that in all your years of living than don't fucking have kids (╬ ̄皿 ̄)凸
No child deserves to be treated that way. No child should be brought up with the thought of assassinating their family. Was there never a single emperor who thought this was wrong?