As I read the Manhwa, the weird dream that Yielle see is probably true. I guess the new wife of that Emperor about to marry is Hansel's mother. Yielle is probably that witch that curse them, because if the witch that curse them were to be pregnant then Yielle would have been half-witch but she isn’t, she’s a pure one. Then the girl got reincarnated and possessed Yielle and didn’t know the whole story and took in Hansel and his sister (not real sister tho), without knowing they were the person's children that she curse. This is what I think in my perspective, I might be wrong but I hope I will get spoiler. And what if Hansel’s mother is actually the Emperor’s sister and not the Emperor’s wife!? This is just a theory of mine but it’s possible because they have the same color hair but different eyes, might be from different mother or the same mother but have one of the parents eyes color.