I've seen a fair bit of chatter about this pairing, and honestly, the number one thing I keep seeing is the gravity reversal trope. It's so specific to them and gets used in a million ways, mostly as a metaphor. Sometimes it's literal—Deku accidentally floats her during a hug and she just laughs, which is cute. But I've also seen it explored darker, like her power failing at a critical moment and him catching her, or vice versa, him pushing himself too far and needing her to bring him back down to earth. It's a built-in physical symbol for their whole dynamic, him being this skyward-bound idealist and her being the one who grounds him.
Another one that's everywhere is the 'pining from a distance' setup during their U.A. years. It feels like half the fics are just variations on Deku being too nervous to confess, or Ochako being convinced she's distracting him from his path to being the number one hero. There's a lot of mutual admiration that gets tangled up with guilt and duty. I've also noticed a weirdly popular niche for 'quirk accident' stories where they get hit by something that forces emotional honesty, which can be fun if done right, but it often feels like a shortcut.
My personal favorite, though it might be less common, is post-canon stuff that deals with the aftermath of all the battles. Fics that explore how two people who've been through that level of trauma might actually build something stable together, with all the scars and nightmares. Those tend to have less fluffy tropes and more quiet moments, like sharing a meal after a long day of hero work, which feels earned.