Blow Out
Written for this prompt on the Avengers kinkmeme (and first posted there): "The Avengers are trapped somewhere. A forest, a cave, whatever. Tony, who is hurt, traumatized, his arc reactor running low, MacGyvers some awesome shit and saves the day. The Avengers can only watch in awe."
The Avengers are stuck in a cave, and Tony, despite being essentially incapacitated by the loss of his suit, has a working plan to deal with this shit. So what if his team thinks he's only useful in the suit? And so what that they're not in life-threatening danger, the kind that Loki strews around himself like confetti? Tony is going to get them out of there by hook or by crook, because goddammit he hates caves, and no one else is coming up with a better plan. They're not in danger now, but time is running out. And if Tony has to damage himself to pull off his plan, well, them's the breaks.
Incidentally, Steve doesn't like it when Tony's damaged.
(Or: Stand back! Tony Stark's about to try science. Dangerous, self-sacrificing science.)