From what i understood, Hwan couldn't heal himself anymore and couldn't turn Sooin into a vampire bcs he was too weak (bcs hes been drinking Sooins blood thats like poison) so he used that assholes vampire blood to turn Sooin into a vampire. I think the reason Sooin didn't become a link to the asshole was bcs he was already dead and so Sooin, now a vampire, gave Hwan (he became human from the poison btw) his own blood to become a link with him.
Idk if thats clear to understand, sorry i can't form sentences very well when i try to explain smth lol hope this helps:)
No no i understand it now
Thank you
Ummmm
The ending was rushed I don't get how the bottom turned to a vampire with the help of the a**hole what did hwan do
I don't get anything
But i don't want it any other way
Maybe some explaining but nothing more