Steve and the Asset (either CATWS era or a recaptured/reactivated Bucky) are forced to fight in some sort of semi-public HYDRA setting - party, room of goons, whatever. The more spectators the better. Winner fucks loser. Holding back results in pain/punishment (mostly for the Asset, regardless of who does the holding back.)
+ One or both of them are already badly injured at the start
+ One or both of them become badly injured in a way that makes the sex painful (Would be interested in seeing whoever tops be injured/in pain tbh)
+ Bucky begins to become self-aware (and subsequently panic) while fucking or being fucked
+ An actual cage isn't strictly necessary. But could be fun!
Steve/WS cagematch fuck or die
+ One or both of them are already badly injured at the start
+ One or both of them become badly injured in a way that makes the sex painful (Would be interested in seeing whoever tops be injured/in pain tbh)
+ Bucky begins to become self-aware (and subsequently panic) while fucking or being fucked
+ An actual cage isn't strictly necessary. But could be fun!