The Steve/Tony stories I love, adore, worship, and have bookmarked for repeat readings! I will convince you all yet of the validity of this pairing!
In no particular order cos they're all fucking incredible (and, you know, lengthy as all get out):
Ready, Fire, Aim 'Verse In a Different Light Magnetic series Honey, I Can See The Stars Tomorrow Belongs To Me There is no 'I'. . . Some Assembly Required A Partial Dictionary Of The 21st Century By Captain Steve Rogers, US Army Arms And The Man