A lot of fics I come across seem to treat them as two halves of the same broken coin, which I get, but honestly, it can get pretty one-note. The popular take is this obsessive, mutually-understood darkness where Toga's infatuation with Deku's blood somehow translates into a deep, romantic understanding of his drive to save people. I've read a dozen slow-burns that start with a rooftop encounter and spiral into them both questioning hero society. It's a compelling mirror, but sometimes I just want a story where the dynamic is... weirder? Less destined soulmates, more bizarre, uncomfortable alliance born out of a specific, messed-up circumstance. Like, what if they had to work together for five minutes on a purely logistical level, with zero romantic subtext, and it was just awkward and horrifying for everyone involved? That could be funny.
Honestly, the influence is massive because they represent such clear, opposing ideologies that still have this strange point of contact through obsession and self-sacrifice. It gives writers a built-in engine for conflict and forced proximity. The fanon version of their relationship has almost become its own archetype within the fandom, to the point where seeing them written as outright enemies with no nuance feels like a rare choice.