Here's what I remember (but could be mixing up more than one fic - I blame fever and cold meds): Tony is the leader of the Avengers post Civil War. He goes to Wakanda because T'Challa offers him Vibrabium as part of a business deal. Tony knows the trip is really about dealing with Team Cap. He gets the Vibranium and leaves after saying he won't help them.
T'Challa goes to the Accords Council and brokers a deal telling them Tony knew where Team Cap has been. Everett Ross schedules a press conference and tells Tony if he doesn't play nice and welcome TC back into the fold, Tony will be removed as leader and/or investigated.
Tony is with Stephen Strange when he gets the call. Dr. Strange, who is part of the Avengers now, brings him by portal to the event. Tony does the most Tony thing possible, that is, he acts like he's going to play nice and then tells the press about the blackmail, etc and then quits. Strange also resigns.
Any help is appreciated!