Tony Stark was my first love in this fandom, so I’m very happy to rec some fic with reasonably significant Tony presence.
One Hundred and Five Percent by IAmShadow21 is a lovely Tony/Pepper, plus comics!Extremis (computer hive mind, not just explosive healing ability), plus bots (’cause bots are the best) kind of a fic. Sweet and funny, and more suggestive than explicit, in my opinion.
The next rec is posted on Tumblr and goes by the name of Hydrocodone Midnight Theatre Part One: The Long Con. It’s a short, awesome Tony/Pepper White Collar crossover by copperbadge, who wrote this while high on painkillers on account of his gallbladder surgery. (He was taking fic requests and dashing them off within minutes. It was like watching genius drunken speed chess. :) )
My third rec is from the archives. Stick together and see it through by torakowalski is Tony&Phil being unlikely BAMF bros, with background Phil/Clint. A bit of exciting action adventure, with reluctant friendship feels. Phil POV.
Last rec of the day is I fix your shit by Eligh. This is a post-apocalyptic AU, Clint POV. The main pairing is eventually explicit Clint/bot!Phil (with a principled handling of consent issues); the Tony/Bruce is secondary, but there is a reasonable amount of Tony characterization. Totally awesome read.