Finding something fresh within a pairing as established as Shigaraki and Dabi feels tougher every year. Most writers default to a few worn-out grooves: hurt/comfort after a battle, reluctant allies forced into proximity, or the classic 'who’s manipulating who?' psychological duel. Those can work, but I crave scenarios that push past the obvious. What about exploring their shared history as failed projects? Not just talking about it, but a story where they stumble onto records of other subjects from their respective 'creations'—Ujiko’s other Nomu candidates, maybe Endeavor’s earlier quirk marriage attempts—and that shared context of being discarded prototypes bonds them in a quieter, more nihilistic way. Another angle I rarely see is them leveraging their public notoriety. A fic where they have to lay low and share a grimy apartment, not for romance, but because the League's safehouses are compromised, and the mundane friction of that is the entire plot. The tension comes from Dabi burning the toast and Shigaraki accidentally decaying the remote, not from grand declarations.
I also think there's untapped potential in a role reversal where Shigaraki’s leadership is more strategic and cold, and Dabi, for all his chaos, is the one who has to be the pragmatic voice to rein in Tomura’s more self-destructive, impulsive whims. Most fics paint Dabi as the loose cannon, but what if Tomura is the one who’s dangerously unhinged and Dabi has to manage him to keep their goals on track? That dynamic feels more true to late-series manga developments to me.