"A kids' story,'said the Doctor. 'Thing is, kids' stories are some of the most gruesome and grisly tales ever told! Grimms' fairy tales! Roald Dahl! Beatrix Potter, even! Toes cut off, eyes poked out or dancing in red-hot shoes for eternity! Put in pies, torn part or, if you're really lucky, just dying of sorrow at the end! If we're stuck in a kids' story, it's not gonna be all picnics and unicorns, I can tell you that now."