It's hard for me to see Tsukasa as an alpha in any way, but I think it would be cute if he gave up being one to become an omega in this case! It's a big decision to make, but both of them want to become a bonded pair, and Tsukasa has always dreamed of having a big family, it's natural for him to become the omega. The process can be painful, and Rui hates seeing his beloved suffering so much at some points but they both become so happy when Tsukasa has finally become an omega and Rui can make him his forever ::>_<:: Rui would be so focused on making Tsukasa comfortable and taking care of the soon-to-be-omega so well... Ah~ Tsukasa likes it a bit too much, to be spoiled like that (❤️´艸｀❤️) He gets used to being an omega pretty easily because of that teehe~