If he'd given it any thought, he would have found the idea of her assessing him as a threat on any level utterly ridiculous. Not that he's completely defenseless or anything. He has pretty good reflexes, and an absurdly high pain threshold; and maybe he's never going to be built like Thor or Steve, or even Clint, but the armor weighs more than he does and steering it in flight is a whole-body process. But he's not a fighter by nature. He'd rather talk his way out of a problem; violence was always going to be a distant second choice.

And in any case, he's seen Natasha fight. She moves like a goddamn snake. He's pretty sure she could take each and every one of them out.

He's trying not to tense, to keep his body language relaxed, but it's not easy. It's all he can do not to shy away when she reaches out toward him. A faint shiver runs through him at her touch, muscles jumping and twitching involuntarily under her fingertips. There's hasn't been a whole lot of human contact in his life ever since Afghanistan, for a whole number of reasons. This is...weirdly intimate, and the strange sort of moment they seem to be having here has the automatic smart-ass remark about feeling him up dying on his lips.

"Arc reactor," he explains succinctly, "Levitating dipole magnetic containment fusion reactor, if you wanna get technical, but that just doesn't have the same ring to it." He glances down at it, running a finger along the warm, smooth metal of the casing; it hums reassuringly under his touch. Tension is still evident in every movement he makes. He hates that he feels so vulnerable like this.