Tony got used to not breathing after Afghanistan. He remembered the agony of it, the black spots in his vision as the world went out of focus, cut through with angry red spikes of pain. He never thought he'd have to do it again.
But if it was to keep Steve safe, well. There was little Tony wouldn't do. Even if it involved coughing up flowers.
A whole bouquet worth of flowers ends up on their bed the night of the wedding, the colours almost sombre. “Well,” Steve says and stops unbuttoning his shirt, “I guess we married for nothing.”
- Tony is dying from unrequited love for Captain America, who is first a dead hero and then a very alive one just as disinterested in Tony as Howard had always promised.
Tony catches an alien disease-- which somehow is the least concerning part of the situation. Bucky wants to spend time with him, only Tony's trying to avoid him so desperately that he gets caught in a lie.
Steve doesn’t mind that Tony doesn’t return his feelings. He just would've preferred if it didn’t come with the side effect of his coughing up flowers and possibly dying.