I'm a sucker for kidnapped!Tony stories. I've got a bunny where a villain kidnaps Captain America's boyfriend Tony to use for ransom. However, they're not actually dating (or involved at all).

If I ever get around to finding some ambition and actually writing, I'd go with ridiculous fluff instead of the angst angle. (Perhaps upon learning the true nature of their relationship, the villain stacks the rescue situation to try to fix the two of them up, abandoning the original plan? I don't even know what villain would be cracktastic enough to pull that off without major canon defilement... except maybe co-opting Deadpool to play antagonist.)