The thing about that fight on the helicarrier is that it really does read at that point, especially towards the end, as Steve and BUCKY fighting and not Steve and Winter Soldier.
I mean contrast with the fight on the Causeway with the fight on the Helicarrier. The Causeway fight is so much skill, it’s hand to hand, it’s knives, it’s Winter Soldier with his mask on, completely devoid of emotion, a total machine. It’s Steve using every piece of hand to hand, the best hand to hand fighter in the Marvel universe showing every bit of skill, utilizing his shield. It’s skilled skilled fighting, it’s knives and slicing and absolutely brutal, no mistake, but PROFESSIONAL. Two people incredibly skilled at what they do, an assassin and a captain.
Then you have the Helicarrier. It’s full of emotion, it’s BUCKY and not Winter Soldier, at least as much as it’s possible at that point. He’s SNARLING, he’s RAGING, he’s so incredibly angry and frustrated and confused. They’re still matching each other completely, blow by blow. Push and pull. It’s Steve going for the console, just trying to get PAST Bucky but Bucky PULLING HIM BACK constantly, pulling him away.
When it goes to the lower level, when it becomes a fight for the piece of data, all of a sudden it devolves completely and explodes into chaos. It’s way too personal at this point. This is not the Causeway. This is one man fighting for his friend, with his friend, one man so dreadfully and terribly lost and confused and ANGRY and lashing out completely and totally. It becomes a grown up version, an incredibly violent and dark version of a school boy fight. A fight between two friends, two BOYS playing keep away in the most violent life destroying way possible. There’s choke holds and head butts, there’s grappling and grasping and pulling. This is not Captain America and Winter Soldier fighting, it’s Steve and Bucky. It’s two friends fighting each other, two children who are so hurt and desperate and angry. It’s two childhood friends who have gone through so much together, so many memories, so much physical sense memory.
You can imagine all the times that Bucky probably taught Steve those schoolyard moves. The grappling, the punching. All the stuff that Steve probably learned in the gritty arena of his activities with Bucky in the European theater. The times they probably practiced together, watched each other fight. The times that Bucky fought off bullies for Steve. This is fighting that isn’t skilled and honed, but ingrained in who they are and where they come from. It’s sense memory, it’s physical memory. It’s a product of emotion and desperation. It’s Steve and Bucky for the first time in a long time, even if Bucky’s mind is not there yet. For the first time in a long time his actions are fueled by desperation, by EMOTION. It’s not the face of a blank fighting machine, it’s the face of Bucky Barnes.