You Can Be Happy (слэш)

Fact of the matter is, Barnes is getting sloppy with the stoic, composed killer shtick. His legs tremble when he’s about to coast over the edge. His eyes go soft when he watches Tony’s mouth. He’ll scratch over Tony’s scalp while Tony sits between his knees. Laughs at about a third of his jokes, which is abnormally high for anyone, let alone a recovering assassin. Tony’s a smart man. Perceptive. He knows it’s not just that his mouth is so talented it can send a guy like him head over heels, though he had considered it.
No, Bucky’s desperate to release the tension. But he won’t bite the bullet and let it happen. 
When that tension becomes a problem in the field, when Barnes goes mute, when he can’t cool off and has to storm around the damn ship for two hours before anyone can safely approach him, Tony decides it’s time for an intervention.