The reality of the situation struck Matthias suddenly. Kaz hadn’t picked up the rifle. Matthias had a gun in his hands, and Kaz Brekker was unarmed. They were standing over the bodies of two unconscious drüskelle, men who were supposed to be Matthias’ brothers. I can shoot him, Matthias thought. Doom Nina and the rest of them with a single act. Again, Matthias had the strange sense of his life viewed the wrong way up. He was dressed in prison clothes, an intruder in the place he’d once called home. Who am I now?
He looked at Kaz Brekker, a boy whose only cause was himself. Still, he was a survivor, and his own kind of soldier. He had honored his bargain with Matthias. At any point, he might have decided that Matthias had served his purpose—once he’d helped them draw up the plans, once they’d gotten past the holding cells, once Matthias had revealed the secret bridge. And whoever he’d become, Matthias was not going to shoot someone unarmed. He’d not yet sunk so far.
Matthias lowered his weapon.
This might be truly a character development, so it's "the old" Matthias, who wouldn't have qualms about shooting an unarmed person, BUT Grisha might simply not count, since "they are ALWAYS armed", right, Leigh?!
