One angle I see a lot is the 'popular but secretly fragile' trope applied to Kita, paired with Bocchi's social anxiety. It's less about romance rushing in and more about quiet understanding – Kita noticing when Bocchi's about to spiral during a social event and pulling her aside, or Bocchi picking up on the subtle cracks in Kita's always-perfect front. They write these tiny, hyper-specific moments: Kita fixing the collar on Bocchi's uniform before a show, fingers brushing her neck, and Bocchi freezing not from panic but from the sheer novelty of gentle, non-overwhelming contact. The themes are all about different kinds of loneliness meeting and realizing they don't have to be lonely in the same way.
Another huge focus is on music as a shared language when words fail. I've read fics where they're the last two in the studio, Kita practicing vocals and Bocchi noodling on her guitar, and they accidentally sync up into something new. The conflict usually isn't external drama; it's internal, about whether this fragile connection they've built in the practice room can survive the brighter lights of the real world. It's achingly slow burn, often from Bocchi's perspective, cataloguing every small proof that Kita Ikuyo, of all people, actually sees her.