OMG!!!!! thank u for this ask ehehe okay so like bg has been a cat the majority of his life and he has lived on the streets, as a cat, so he behaves like one bc he doesn't know anything else!! here comes yj, in his pajamas and a fox headband (bc he was doing his skincare) taking out the trash, so bg approaches him bc he hasn't seen any hybrid ever and thinks yj might be one too, but yj looks at him and just coos at him and talks to him in a baby voice and bg is thinking wtf is this guy doing and saying.... yj takes him home and takes care of him while bg just... lets it happen bc this human (who apparently is not an hybrid) is treating him SO gently and is SO caring and bg is so tired of living in the streets...
eventually bg feels more safe than he's ever been and one night he just transforms into his human-like form randomly while sleeping.

and their shenanigans begin!!!!!!

I have a lot of ideas and I'd like to make it into a series of comics (hopefully) and yeah there's more lore but and things but I don't want to spoil everything that happens sooo