@Enexin Based on the ending pages I don't think they care about the twins at all. They're just trying to use the royalty's attachment for them as a mechanism to damage the royal family.
I like that they're a means to an end rather than some silly straightforward "hurr-durr impure blood must purge" nonsense. Actually makes the antagonists interesting.
didn't the fox dude thats supposed to protect them show up once before in front of the emperor? why's he in water now... so confused on this part is he sealed or something.