[Despite the threat, James actually seems slightly more relaxed. If this Bucky is worrying about that, about losing control, that's good. That means he's past being someone's puppet, that he's aware of himself.]

I'm not asking you to trust me. [That would be way too much for either of them.] But you don't know what I am. Where I am. I've been back in the world for a while by now, they don't have a hold on me anymore. [Or, they only do in his nightmares.

He gives this other version a searching look and says evenly, without judgement,] I won't be the one to lose control.