My guess is that the mom could be a spy? They were so wary of Elsa at the beginning that I couldn't help myself to think that they already experienced betrayal from a very close person before (which could be the kids' mom). It also seems that there's some kind of a curse (?) that makes a child of the duke's family unable to disobey the emperor. Although the probability is like, only one for each generation. I think that kind of child is what the emperor wants so he schemed for the children's mother to marry ML's brother and give birth to a child like that. However, it might be that their schemes were found out before she could give birth to that kind of child. So he commands FL's family to send her to the new duke to be his wife and increase the chances of acquiring that child.
This is all just a guess tho. I also have another theory that the women who marry into their family suffer health issues in the long run, which again may be related to the duke's bloodline (as it is heavily implied, I wish they would just reveal it already
Ah I see that would be interesting, I also want to see the mom come up in the future, how that interaction would be.
I thought their(〜￣△￣)〜 dad was dead and their mom wasn’t ? In ch 2 the butler says the lost their dad, uncle off to war and their mom was weak and is recovering in a warm climate? So is she or is she not dead? I know they have said multiple times their dad is dead but rarely anything is said about their mom??