I have written other Clara theories. I started out thinking
she was the Doctor's granddaughter. I also had lots of thoughts on whether she was a [Gallifreyan] egg or a bird or
something. Possibly a TARDIS. (See my
Clara Who tag.)
This theory, however, has appeared/worked its way to the top of the pile, quite simply by being so gosh darn constant (from her first appearance to her latest), and by being so blatant that I worry I'm imagining things. Is it all co-incidence or Moffat trolling? (Well, whatever the case, he is a troll. The Top Troll of all time.)
But onwards. If you've been following my meta, this should not be much of a surprise. I think...
ETA:
WELL THAT GOT DEBUNKED QUICKLY! Although I did have a good point...
"When I first wrote Clara, I thought, “Oh, this is fun. If the Doctor were a young woman living in contemporary Britain, it’d be a bit like her.” Moffat
(Unless he's lying with the truth.
Again.)
( Clara Oswald Never Existed )