(This is a comment I just left on AO3 at Kenopsia's request, for a friend she was trying to recruit to the fandom. I doubt this has helped her but I DIDN'T WANT ALL OF THIS WORK TO GO TO WASTE, sob, so I'm just crossposting it here.)
Inception fandom is super-wide-ranging, and all the fics are so good. It's really honestly harder to find a bad fic in this fandom than a good one regardless of what the trope/genre is. And if you like long fic there's a ton of that also. The vast majority of the fandom focuses on Arthur/Eames, but there are plenty of fics about other pairings in the inception ensemble cast, too.
Basically there are 7 kinds of Inception fic:
the backstory fic (that's usually about the origins of dreamshare / stuff before inception, or arthur and eames' shared time in the military, or a mix of both). (These are also often angsty as fuck, but not always!)
Over-time fic that explores the team's relationships (usually before/during/after inception) that usually involves a lot of pining and/or on the job fucking with Feelings and Miscommunication (this fandom is full of fics where the OTP pines for each other for like, a literal decade, haha, it's intense), or else a lot of Arthur and Eames perpetually saving each other and being badass and kicking ass/taking names while having tons of UST and unspoken partnership and/or Misunderstandings and/or temporary break-ups before finally admitting they're in love and fucking it out. (And occasionally a fuckton of domesticity, either by surprise, strategically, accidentally or otherwise. ♥)
crack fic (often handled seriously) where something goes wrong and one of them gets incepted into believing they're a cat or a dog or Satan, or the chemist accidentally gives them a love potion, or a truth drug, etc etc etc
a canon AU where the world still ultimately is the same as in the film but something crucial or significant about the universe has changed, like the fic where Eames is actually Calvin, or the one where Arthur is actually a purple squid ♥♥♥, or it's canon but mpreg, or it's canon but alpha/omega, etc etc.
The mindfuck. Fic exploring the ambiguities of the universe—fic where you don't know what's real, fic where you don't know if you're real, fic where the events of inception were all a dream, fics where Mal Was Right, fic where the forgery threatens to eat away at your sanity, fics where you're lost in limbo, fics where you're lost in your own mind.
your basic 'we need to fuck right now,'no seriously right now, and preferably repeatedly' PWP
the pure AU. inception AUs are absolutely glorious.
This fandom really likes making lists and crowdsourcing rec lists, and there are a bunch of extremely long inception fic rec lists floating around (mostly for a mix of fics on AO3 and LJ—and the side of the fandom that is only on LJ is seriously phenomenal) which can help you find fics. :)
Good luck!
