Kill to Love

poison spy martial arts emperor arranged marriage prince forbidden love heir to the throne revenge romance flashback royalty betrayal family relationships snow historical fiction historical tragic past political intrigue  childhood friends family power struggle crown prince scheming wuxia hidden identity power struggle angst palace intrigue assassination attempt marriage of alliance costume drama master servant relationship evil brother hidden agenda gay romance death of a loved one toxic relationship brother brother relationship historical romance friends reunion war skilled fighter friends to lovers boys' love (bl) court intrigue siblings reunion long lost sibling based on web novel lovers to enemies