I'm, like, 98% sure it was steve/tony, but I suppose I could be mistaken and that's why I couldn't find the fic.
Basically, the Avengers are having a big paintball game in the Tower which Steve(?? We'll say Steve) is unaware of. He comes home and sees Tony covered in 'blood' (red paint) and has a panic attack, I think.
If this story has been removed, does anybody have a copy they can send me, or at least the old link so I can try and find it via the wayback machine.