There's one which is just an eye peeking out from behind a stack, but that eye - or rather, that eyebrow - is very, uniquely distinctive.

Isaac can't help but smile at that crazy grin though. And instinctively start a fresh page, eyes misting over white as he talks and starts to draw. "Right, a hobby out saving people."

He draws the Doctor smiling in a few sharp, defined lines. And then draws him again, shaved head and big ear and hawkish nose, same mad grin.