If anything, the way this version of Itachi walked wasn't too far from the way the Itachi he knew walked. Group Captain Uchiha Itachi was stealthier than an F22 Raptor even with boots on gravel or dry grass.

And Shisui did retaliate in one swift motion just as the 'fake' Itachi almost touched his face. There was a sharp blade held up beneath the other's chin near his trachea, not pressing into skin just yet but just-- there. Shisui didn't need a blade to sever a man's head - he could do it with his fingers - but this was just for precautionary measures. "It was just an explosion. I'll be fine."

Shisui does not take his eyes off the other man for a moment, the fact that he'd been given a somewhat sad smile at all only a moment ago still eating at his conscience and playing with his current state of mind. Where was the real Itachi?! "I'm talking about things the real Itachi would know. And you're not him. I'm not buying your bullshit about overlapping timelines, either." At least, not without substantial proof that it is so-- but he keeps that to himself. "So what's the name of the fancy drug you've got pumping through your prisoners of war, huh?"

He'd love to know.