What I remember (pretty sure it's movieverse):
- Steve, Clint, Natasha are sent on a mission, with Coulson as their handler, to fight The Wrecking Crew; they figure they can handle it because it's just the Wrecking Crew trying to rob a bank. Bruce and Tony are across the (bay? some body of water) doing some sort of Science Convention (multinational - my brain is apparently mush...). Thor was somewhere else, sort of nearby, doing some charity event (with kids?) However, they didn't realize that...
- The Wrecking Crew was stealing a dragon egg. That then hatched. In the bank. And grew. They call for back-up; Steve gives Clint a boost so he can get to a rooftop. Clint's firing arrows and nothing is phasing the dragon much; Thor's too far away; Tony is saying something like "I'll be there in x-minutes" Clint says "I don't have x-minutes", Tony says, "I'll be there in x-1 minutes" and Coulson says, "This is not a ____!" and Tony says, "Fuck it, I'll be there in x-2 (or x-3?) minutes?"
-Clint then says something like "I'm going all Mulan on it."
-Steve doesn't get it. Coulson yells "No!"
-Clint goes all Mulan. Arrows explode. Clint falls off the building, still shooting, debris falling all around him, the bank collapsing around the dragon.
-Tony comes flying in at the last minute, catches Clint even as he's shooting the last arrow; almost makes it clean, gets clipped in a boot by a debris that would have killed any of the others, and goes spinning - can't get control because he's holding Clint and one boot is shot.
-Thor comes in, Tony yells something about lateralling - tosses Clint to Thor, and drill-bits into the ground.
-Dragon comes up and goes to eat Tony, Steve throws his shield, knowing it'll be too late, and Tony throws up a foot and gets the Dragon in the face, which sets off the last arrow, which leave the dragon less half a head, and dead.
-They come running up and Tony is refusing to open his helmet, freaking everyone out - Coulson is running up, tie flapping, the most ruffled they've ever seen him - and turns out Tony puked in his helmet which is why he didn't want to open it. Clint sags in relief teasing him - saying he puked twice and they must have pulled 3-G's.
.... I remember a lot. I don't remember anything useful such as oh -I *think* it's Steve/Tony, but I'm not altogether sure. And I don't remember anything useful like the author or, y'know. The title. or for sure where I read it, though I suspect AO3.
Like I said, I am going to *headdesk* so hard when (I dearly, dearly hope) someone finds this for me.