I really feel like this image perfectly describes these two without even saying anything.
Bucky is the offense, Steve is the defense.
They’re both staring down Tony, Bucky has him in his sights ready to strike at a moments notice and Steve crouches with the shield ready to protect against anything Tony might throw at them. And this shot is so beautifully framed that you almost can’t tell that it’s two people. It just looks like a single being, posed, cautious, but ready to attack if needed.
And even later in this scene when Steve approaches Tony, shield still raised, and Bucky still standing on the steps with his gun raised it still seems like it’s just an arm being outstretched from the body.
And to think about how despite everything they’ve been through, being separated all this time, they still fall back into this familiar dynamic they always had - Steve and Bucky against the world. Inseparable.