i think xunfeng loosing his memory has the greatest potential because: 1) your brother whom you want to kill now loves you; 2) your sister-in-law is a pesty fairy, which you hate; 3) you are married to your mortal enemy (changheng).
ok but this is already a 20k fic in my mind which i won't write because literally nobody is into this pairing, but let me tell you a bit about it!
xunfeng loses his memory battling a spirit during a mission in a snowy field with changheng, then he wakes up while changheng is taking care of him and starts a fight
the only way changheng can calm him down is accepting to go back to cangyan sea in immortal-binding chains. xunfeng is so pleased with himself for having captured the moon tribe's greatest enemy and expects to receive great honors, but when he arrives he finds his scary brother, who has retaken possession of the throne, who just goes with the dumbest face 'why did you chain changheng???'
and then changheng has to pretend to just be a good friend for like two months until xunfeng falls all over again and understands on his own that they were lovers
'were we lovers?' 'yes' 'were we hiding it?' 'not really, because people from the moon tribe and the fairies can be together now' 'so everybody now also knows i like men?' 'well yes'
and changheng just doesn't want to tell him they are married yet, because he doesn't think it's still valid if this version of xunfeng hasn't consented to it
UPDATE! I'm currently writing it HERE
