from what I understood he’s the king of prince from the imperial family and he’s adopted in that clan
LOL no not at all. sects can bring people in and they'll be "family" cuz they're in the same sect or clan but won't be blood-related or even rasied-together related. in this case particularly, they aren't at all he's part of another family that he knows and had to leave that family so her maternal side of the family took him in eventually after that. also oraboni is an ancient way of saying older brother but thats cuz that's it's an older form of korean address for a younger girl to a slightly older guy - modern version would be "oppa". they call all older guys (like only guys under like 20yrs older than them tho, past that they have like other terms of address) that they are very close to that.
anyways, it totally all may sound weird, and at first may seem real albama cousin pontentially but they clear it up pretty soon after
Are her and the oraboni dude related?? I'm confused about that, I thought they were, but then like. They're romantically involved, so like I was like, whuh?