Civil War au where, instead of Team Cap v. Team Iron Man (and I have a lot of Feelings about both their motivations' in that movie, but that's a whole different post), it's Team Falcon v. Team War Machine. They seemed to be the most dedicated to their respective positions. They didn't appear to have any personal matters affecting their choices. They're the modern military men (and without Steve, which I think would also remove Bucky from the whole scenario, they'd be the only military people full stop).