The fact is that despite everything that Zero and Ocelot had implied to him in their various conversations, Miller does know Snake well. Maybe they'd only worked together for a couple of years, but sometimes it's not the length of time spent with a person that matters. They'd built something together, their skills complementing each other in a seamless way to create MSF. What they'd had then, it had been good, and it had been theirs.

The point being that Kaz knows Snake well enough that he can tell when he's actually gotten to him. The signs are subtle, but they're there, and he doesn't know if he should be triumphant or upset to have gotten that kind of reaction out of him. (It's not easily done.)

Of course, Snake comes back with something just as cutting, and Kaz can't say that he hadn't been braced for it. It still pisses him off, even though he knows that now both of them are just picking their words for how sharp they are, for how much damage they think they'll do.

"Is that what you think?" Kaz bows his head and shakes it, the tension draining out of his shoulders as he lets it all sink in. "That you could just send me some copy, and that'd be good enough? You figured, what, I wouldn't notice the difference?" Just as fast, his head snaps back up so he can look Snake right in the eye. Thankfully, his sunglasses stay on firmly. "Don't you get it? He wasn't you."

Whether or not Snake had realized what he was doing, he'd left Kaz with another scar, another piece missing. Maybe it's not as visible as his empty sleeve or peg leg, but he feels it every goddamn day.