Both part of Imperial but different family in short not related. There are a lot of families the Imperial consist not just the Emperor and it's relatives.
Spoiler!
i read that they’re not the same part of the imperial family. or like they’re really distant or something like that!
lol we replied at the same time but ty for this! your answer is much clearer
Spoiler
No incest, they’re not blood related at all! I think Frey and Aria’s dad are actually half siblings, if I remember correctly. It’s a bit long but I can spoil the full story behind this if you want lol
hehe yeah. Some people think that the Kingdom or Imperial is just have the Family of the King or The Emperor but they didn't know there are lots of Royalties there. Nobles are also part of Imperial. In short Aria' Father's family is a noble.
If frey is of the imperial family (i think) if aria is the child of that man isn't it incest between her and asher? Not that i care at all, it being fiction, but still