He knows that sound, even before he can parse anything else. SecUnit. The rescuer. Foolish of him to attempt this here, so close to the Convoy: he didn't think, didn't plan. Humiliating as it is, he does not like his odds.

And... this person helped him. Saved him, when he was trapped and wounded. It is one thing to strike down an immediate threat, and surely anyone who can look upon him and speak the King's name is a threat— to the life he has built here, to his odds of ever getting Arthur back. To everything. But to raise a hand against his rescuer, merely for getting in the way?

As his old self, John would not have hesitated an instant. For that reason, he keeps his hands splayed in surrender.

"I..." The mask betrays no emotion, but there is agitation in his voice and the hunch of his shoulders. He grits an apology through unseen teeth. "I'm sorry. Alright? Don't fucking shoot, it's... it's passing."

He has been on the receiving end of two rampages, now. Surely he's earned the excuse.

"Just give me a fucking second to think straight."