Tendou and Ushijima are such a fascinating pair to cross over because they both have this kind of... clinical precision that can translate into so many other genres. Their dynamic of Ushijima's blunt, straightforward power and Tendou's unpredictable, almost unsettling intuition is perfect for putting them in a sci-fi or cyberpunk setting. Imagine them as agents in a 'Ghost in the Shell'-type world—Ushijima as the unstoppable, by-the-book cyborg, and Tendou as the hacker who bends the rules of the net. Their volleyball court partnership becomes a tactical unit, and all that intense mutual respect gets filtered through a new, high-stakes lens.
Horror is another one that clicks surprisingly well. Not just jump scares, but psychological stuff. Tendou's 'Guess Monster' schtick and his ability to read people borders on the supernatural. Drop them into something like 'The Magnus Archives' or a cosmic horror scenario, and you've got Ushijima as the unshakeable anchor of reality and Tendou as the one who perceives the cracks in it. The tension between Ushijima's absolute faith in what he can see and Tendou's perception of what's hidden could be incredible.
Fantasy AU is the obvious classic, but to make it work, you really have to commit to a specific role. Paladin and Warlock is a personal favorite—Ushijima, the chosen warrior of a lawful good deity, bound to a code, and Tendou, who bargained for his power from something older and stranger. Their loyalty to each other would constantly test the boundaries of their respective paths. The magic system becomes a direct metaphor for their volleyball skills, which is a fun way to keep their core dynamic intact while the world around them changes completely.