Dean was sure that his sword would reach Law's throat. The calculations were precise, his movement was fluid and fast, he didn't waste motion, nor did he hesitate. That was the perfect slash, the final attack of that battle... or so he thought.
His attack didn't hit anything in the end. Law... wasn't in the same spot where he was before. On the contrary, he appeared behind Dean, swinging his dagger once again and aiming at his back. He couldn't kill Dean, even though he wanted so much to do so. He knew that he had a clear disadvantage while fighting against someone who was trying to kill him, while he couldn't fight with the same intentions, but orders were orders.
'I won't let you get away with it, you brat!' He thought as his purplish blade descended.