Honestly? The whole 'opposites attract' thing gets played up a lot, but I think there's a more interesting layer writers lean into. It's less about their Jounin Sensei vs. Academy Student dynamic from canon and more about two people who wear masks to get through the day. Kakashi's literal, Mina's metaphorical, but they're both hiding behind a performance. Most fics I've read explore that—who they are when they finally let the act drop. The forced proximity trope is huge, obviously. Mission assignments, ANBU cross-training, that kind of setup. You see a lot of 'he sees her as more than just the bubbly class clown' arcs, which can be sweet if done right, but sometimes it just feels like the author erasing Mina's canon intelligence to make Kakashi the 'discoverer' of it, which bugs me.
Weirdly specific trope I've noticed: Mina getting injured protecting someone from the Konoha 12, and Kakashi being the one to find her. It happens so often it's practically a genre convention. It's a shortcut to vulnerability for both characters, I guess. Ends with Kakashi reading his book outside the hospital room or something. Cliche, but I've clicked on every single one.