I have always been intrigued by a bit of dialogue Xayah and Rakan share where Rakan asks Xayah to marry him, only for her to tell him to ask again tomorrow, seemingly everyday. I took this contest as an opportunity to explore why that is and when this tradition started.
As research I went back through all their lines, stories, and cinematic again. The Aphea Waterfall is a significant place for them but not explained why other then exchanging vows there. This seemed a good a setting to tie in further with the cannon lore and their characters.
As for the narrative itself I decided what happened at Aphea should be either very romantic or dangerous/near death, to be so memorable. Seeing as much of their romantic side is already explored through the lore, and dangerous is much more interesting so I went with that.
For the characters themselves my goal was to explore what is past Rakan's laid back playful attitude, and to explore Xayah's more uncertain side when she doesn't have plan. Both of these have been hinted in their lines and stories and make their characters much more interesting to me.