So. I'm 90% it was a prompt on the kinkmeme, but alas I've gone through all the filled posts and haven't found it again, so maybe it's on AO3? I DON'T EVEN KNOW. But it's the typical, 'team gets kidnapped' plot, only not. The team minus Tony get kidnapped, and then he shows up to 'rescue' them but not in his armor or anything. Whoever the bad guy of the week is (but it's not Loki, I know that for sure), tells Tony he's free to leave, but then the rest of them will die. All the bad guy wants is Tony's arc reactor, given up willingly so his friends will live. So Tony takes it out and gives it to him, and the bad guy leaves. Then Tony gets all hurty and dying-y, but then Coulson and co. show up and rescue them all.
I loved it and it was really well written and all I want in life is to read it again. If someone can help, yes, you will have my undying devotion. Thanks in advance.
Edit: Now with 100% more tags!