His role's weirdly flexible, which is probably why he pops up so much. I've read fics where he's just a background guy cracking dumb metal puns during the Class A vs. B arc, and others where he's a central emotional support pillar after, like, a hypothetical war arc trauma. He's not overexposed like the main trio, so authors feel free to mold him.
A lot of people latch onto his rivalry with Kirishima. It's a friendly mirror match, and that 'hardening versus hardening' dynamic gets explored in every possible way—platonic life partners, bitter competitors, even romantic rivals. I've seen fics where his unshakable, straightforward personality is used as a grounding force for more volatile characters, like Bakugou or even Todoroki. He’s the reliable rock, literally and figuratively.
Sometimes it feels a bit repetitive, honestly. The 'dense but fiercely loyal' schtick can be one-note if the writer doesn't dig deeper. But when they do, and touch on his insecurities about being a 'copy' or his drive to prove himself, that’s when he gets really interesting. He ends up being a vehicle for themes of self-worth, which I think resonates.