I'm honestly still catching up on the manga itself, but from what I've seen scrolling through Archive of Our Own, there's this intense focus on vulnerability wrapped in all the wild chaos. Like, Okarun and Momo have this whole 'body-swapping alien ghost hunting' thing going on, but the fanfics I've clicked on zero in on the quiet moments after the terror. It's less about the giant fights and more about two people who've seen the universe's weirdest, most horrifying sides and now have to figure out how to be normal teens around each other.
A lot of writers seem fascinated by the idea of two characters who are fundamentally outcasts finding a mirror in each other. Okarun with his social anxiety and Momo with her hyper-competent yet emotionally guarded demeanor—the fics explore how they slowly dismantle each other's walls. I read one recently that was just them sitting in a convenience store after an exorcism, not talking, just sharing a bag of chips while their adrenaline crashes. The emotional core feels like safety, this profound, hard-won sense of being home.
Another big thread is reckoning with past trauma, which the series hands them in spades. Fanworks dig into how they might trigger each other's fears accidentally, then have to navigate the fallout with a clumsy, genuine care. It's never smooth or easy, which makes the connection feel earned.