Doctor Who: 6 Ways Last Christmas Showed Clara's Perfect With The 12th Doctor

5. '12' Is A Good Number

Upon the realisation that the 'scientists' in the North Pole might actually all be part of a dream, the Doctor administers the Helman-Ziegler test to prove to them that it's not real. The way he used this test was by using their station guides - he had them flip to a random page and to each read the first word. As none of the scientists had memorized their book, they had no way to know what that word would be and therefore, each word was different. In the final administration of the test, the Doctor asks Clara for one final number and tests her 'to make it a good one'. She looks toward the Doctor and with a slight smile and states the number 'Twelve'. Why is this important? Peter Capaldi's take on the Doctor is the 12th incarnation (at least in the numbering system used in Doctor Who, anyway - technically he is the 13.5th, but that would be too much, even by Doctor Who standards...). As such, it shows the fans that she truly cares about this Doctor and in turn is implying that 12 is indeed a good one, suggesting he's a good man, too.