Hmm... well I want it to include Ienzo, my OC Kira, your OC Jai, Lumaria, Arlene, basically a lot of the Birth By Sleep characters.
Hmm... the start of it could be Even finding the body of Kira outside the castle, who comes back to life in his arms, despite wounds which heal rapidly, causing Even to study him. Ienzo gets jealous of Even's affection, but Kira doesn't understand any of them (his people have a different language), and tries to hurt Kira but Kira misunderstands and gives him affection. Lumaria and Arlene are there to just torment them. Perhaps Ienzo and Kira could be diapered. But that is one of my ideas. Do you have a specific plot that you want to do?
I'm open to suggestions.