He hadn't seen the cat sneaking up on them, distracted as he was with trying to free Gabriel. And as he'd only just moved the gun, having it jump into Gabriel's hand was rather unexpected, the Doctor's eyes going wide as he watched the man shoot the beast that had been about to leap at him.

He stared at the felled beast for a moment, shook his head, and scanned the area for more of the creatures. He made no comment on the trick; there were more important things to worry about than how Gabriel had managed it, but he'd certainly keep it in mind to ask about later. The Doctor took the gun from Gabriel's hand and kept an eye on their surroundings, just in case any more of the cats tried to creep up on them. Hopefully his friend could free himself, otherwise they were in a bit of a bind.