Honestly, same, that's what I'm into too. I prefer the uke to be smaller and that's coming from a person that's quite short too. I prefer to be taken/ravaged lovingly and passionately, (not domineeringly), by a person that's bigger than me, no hate, just my preference. My absolute favorites though are those small ukes that are very fierce or feisty or an absolute power bottom. I really adore these types of ukes. Maki, Momo, Jinwon, Dojin, Ingyu, Makino, etc. I love them all. Pair them with those semes that are loving gentle giants but are so carnal in bed like Yata, Kamina, Shin, Ethan, etc. and boyyy do these type of pairing's gap moe riles me up so much.
So if Seolhyun is a female lycan and his brother was actually the male lycan and his parents wanted them to be together...sorry, I can't see Seolhyun as the uke with the brother.