Darcy & Tony
There is very little blackmail in existence that actually works on Darcy Lewis. Tony is very, very dismayed to find out there is another person in the world who pretty much never does something she won’t own up to. He also takes great delight on finding out the very few things that she won’t admit she has done and holding them over her head.
Rather literally in regards to the printed out copies of that five page book report on Steve Rogers and the Howling Commandos. Its not so much the actual report that she’s embarrassed about, more so its the unedited copy that her mom traded to Stark for a trip to the Bahamas. There’s tons of little side notes on how hot she thinks Bucky Barnes and Steve Rogers are. And Peggy Carter to. The amateur smut she wrote staring the three isn’t something she ever wants to see the light of day.