
Seolhyun's mind was manipulated. He is a pure blood female lycan but the people around him lied to him and manipulated his mind so he thinks he is a male(but thats not true).
He marked Hwa way before and Hwa marked him too as well. The brother is a male lycan not a female, he smelled the mark's scent(well something like that) on Hyun that's why he is angry. (because the pureblood clan wanted them to mark each other and be together just to keep the pureblood line. Thats why Hyun lived with his brothers family but in reality he is not his real family)
This is whats going on if im not mistaken. But correct me please if im wrong ><
I hope I could help and sorry for my bad english

Yes they erased his memories about Hyun because they don't want any relation between those too. But it was nececcary to manipulate Hyun's mind too from the point of view of the clan leader because they want to keep the pureblood line that much. If Hyun thinks he is a male he wont look for another male lycan(like Hwa even though he is a hybrid(half vampire half male lycan)) so when the time comes he should have marked his brother and breed so they will have pureblood babies. (This is important for the clan because they already lost Gok they don't want to lose another female, even though that's already too late nowxd)
I read the raws and they will explain it more so just be patient and u will understand the situation more^^
Okaaaay okaaay let’s stop here for a minute why does our hwa I think was his name that hyung is the female lycan and when the supposed to be brother who is also supposed to be a female lycan passes by hwa he said that he was a male ???? Did they lie to them ?????