Man, thinking about Yoruichi and Kisuke tropes always brings me back to that late-night scrolling feeling. The canon gives us such a rich playground—they've got that deep history, the secretive partnership in Soul Society, the years apart, and then the domestic-but-not setup in the shop. For me, the absolute best stuff leans into the 'unspoken things' between them.
I'm a total sucker for the 'established but hidden relationship' trope. Fics that explore them already being together during their captain days, but having to keep it under wraps because of politics, or Yoruichi's status, or even just Kisuke's paranoid nature. The tension of stolen moments in empty corridors, of codes within mission reports. It makes their later reunion hit so much harder.
Another favorite is the 'mutual pining during separation' angle. The thirteen years Yoruichi was in cat form, living with him? The potential for quiet, yearning observation is insane. Fics from Kisuke's POV, where he's talking to the cat, not knowing she understands every word, are a special kind of gut-punch. And then the reversal after the Arrancar arc, with Kisuke injured and Yoruichi being the one watching over him. It's a perfect setup for roles reversing and all that buried care finally surfacing.
Honestly, I'll read almost anything for them that isn't straight-up OOC fluff. The complexity is what makes the ship.