I saw in the comments somewhere that she is only 4 years younger, so it's actually not a big difference. They just see her as being small and all of them dote on her a ton.
It looks like they have at least 10+ years between them.. and still 15y is young
I dont think that emperor has romantic feelings towards her, well at least not yet.
They fall for eachother when shes an adult
Ok not what i expectes but im looking forward to it.
It would be so cute if the king and Nina had a dad/daughter bonding. And brotherly with others, y'know she is way too young for them