He hadn't been paying enough attention. He had been distracted. He heard the sound of the trigger too late and when he moved, he only managed to get hit in the shoulder rather than square in the back. The impact had him stumbling forward a few times before he fell forward into a tree. He used his arm to catch him from faceplanting into the tree as he let out a half shout, have growl that wasn't entirely human.
It burned. Scott had enough experience being shot that he knew it wasn't just a regular bullet. He managed to bring himself around the tree so he wasn't in danger of getting shot again - at least not right away. He leaned heavily against it, his breath was laboured. "You don't have to do this!" He managed to shout it before he winced again.