Rob jerked slightly from the sounds Dean made followed by Mary's; well, they didn't exactly have the upper hand in surprise anymore, did they? Rob knew as much when he'd heard the shot. He paused for only a moment to gather it all in and race to Mary's aid.
The killer was a woman, as Max had thought, and Rob didn't think twice about moving in and toss the crazy woman aside. He didn't do more than that to hurt her; he wouldn't. She was human. They only ended the supernatural types, or that's how he worked.
He gathered up Mary, carefully and quickly moving her to safety. Johnny looked like he was...not in need of as much safety. The cowboy was the on who'd been shot perhaps.
"It's okay, Mary." His voice reassuring. "It's okay." Or it would be.