The Doctor backed further away, staring down at the Master at the Master as he did. He said nothing for a time, just letting him carry on bashing his own head. Their bodies weren't particularly fragile, and he knew it wouldn't harm him really, but after a minute or so of it he'd had enough. Even someone of their species couldn't be allowed to just bash his head against the ground indefinitely. He was a bit hesitant to approach after the last little stunt the Master had pulled, but soon enough, he found himself approaching anyway and gripping his shoulders in an attempt at preventing him from continuing. "You're gonna have yourself out of it for days if you carry on like that."