So there's a new door right? Is it true that the seme will look for another door?

Or the opposite?

what do you mean by that? these two will always be togehter, but if you mean like a ''new'' door, you meant the doctors?

No i mean someone will use the uke for door other than cain

From what I remember, no. There was when Joon woke up the Cain look a like (forgot if that dude's Satan or the other long white haired guy lol) in the room, but they didin't do anything. He just loocked Joon up (for now).