for Byakuya x Ichigo, certain plots just keep rising to the top. The classic is the forced-proximity scenario, like a joint mission gone wrong or a binding spell that links them together. It's such an easy way to get that rigid politeness of Byakuya to crack under the strain of Ichigo's relentless, straightforward energy. You see a lot of 'enemies to reluctant allies to lovers' arcs built on that framework.
Then there's the post-war recovery trope, which I think works better for this pair than a lot of others. Ichigo's lost powers or Byakuya's injuries after a major battle create a dependency that flips their dynamic. Byakuya, forced to accept help, and Ichigo, learning patience and a different kind of strength. It allows for a quiet, almost melancholic build that feels true to the series' tone.
A less common but fascinating one is the role-reversal or alternate universe where Ichigo is a noble or a seated officer in the Gotei 13. Watching Byakuya navigate Ichigo's chaotic influence within the strict hierarchies he upholds is a goldmine for tension. It sidesteps the obvious power imbalance and lets them clash on ideological grounds first.
The plots that usually fall flat for me are the outright OOC domestic fluff too early on. Their relationship, in any form, needs a foundation of earned respect and a lot of heated arguments. The best fics I've read make their first real kiss feel like another form of combat, and that's the specific thrill of this ship.