They both have Suu, the dragon and The prince. This is closely related to the threesome because Sue is in between Sahara and Suryeon. Sshara can't eat Suryeon's blood directly but he can get his food through Suu. And also When Suu was eaten by the dragon he is weak and Suryeon heals him.
So, just give me 3P already LOL
AFTER READING SOME COMMENTS,
This comment might contain spoiler.
I'm just wondering now that Kwon might know that Taejoon is waiting for Yoon .. why didn't he contacted him when he knew that Yoon still alive though. Because everyone says that Taejoon didn't know whether Yoon is still alive and has been hospitalized for 5 years... but from the last raw, I think Kwon said that Taejoon didn't remember him because it just too long that Taejoon contacted him in order to search for Yoon. Kwon help bringing Yoon back to Taejoon but he ditched him.
I think I read someone spoil this story at the very beginning that Yoon decide to left to the war zone again or away from both the ex and Kwon Sunbae. After that Kwon will go find him and confess his love so, Yoon will end up with kwon but before that I think Kwon sunbae also make his life fuckup because he made promise to his ex wife that they will be a married couple on the public. What a mess up is this! I feel like they all look at the love in different way... at this point we reader can choose what right or wrong.
I feel really bad for him, doing such unwilling task. I hope the seme help him get through all that shit in his past life.