Here's the amazing quote from Steven Moffat:
“We are aware that Peter Capaldi’s played a big old part in Doctor Who and Torchwood before and we are not going to ignore the fact.
“I remember Russell [T Davies] told me that he had a big old plan as to why there were two Peter Capaldi’s in the Who universe: one in Pompeii and one in Torchwood. When I cast Peter and Russell got in touch to say how pleased he was, I said, ‘Okay, what was your theory and does it still work?' and he said, ‘Yes it does. Here it is…’"
(Moffat apparently really likes the phrase "big old.")
So let's see: there's a plot arc that was started by Davies and will be fulfilled by Moffat. What?! That could be a pretty fantastic idea. Or pretty horrible. It depends. If you've read this blog through, you should know about my strongly mixed feelings on Davies. While a great show runner, his individual episodes were often...silly. His ideas for how the show should run as a whole, however, were excellent. So to have one of those ideas carried out by a much better writer is a great prospect (assuming that Series 8 isn't anything like Series 7).
So this opens up a new mystery: What do Caecilius and John Forbisher have to do with the 12th Doctor? God, this is just the kind of Doctor Who mystery that I love to speculate about! Thank you, founding fathers of New Who!
“The face is not set from birth. It’s not like he was always going to be one day Peter Capaldi. We know that’s the case because in The War Games [sic] he has a choice of faces. So we know it’s not set, so where does he get those faces from? They can’t just be randomly generated because they’ve got lines. They’ve aged. When he turns into Peter he’ll actually have lines on his face. So where did that face come from?”
Good point, Moffat, but not the best example to illustrate this point. In "The War Games," there was a choice of faces because it was a forced regeneration. The Doctor was being forced to regenerate as a punishment by the Time Lords. They gave him a choice of faces. I always took it to mean that the Time Lords had a special way of forcing a regeneration that would allow them to pick his face.
There are two much better examples, though. One is Commander Maxil, the Time Lord guard who oversaw the attempted execution of the 5th Doctor in "Arc of Infinity." Commander Maxil was played by Colin Baker, who would later go on to play the 6th Doctor. This led to Colin Baker commenting that he was the first actor to get the role of the Doctor by killing off his predecessor. But why did the Doctor regenerate into Maxil's body? Did he have a choice? If so, why choose such an insignificant person in his life to regenerate into? Not to mention such an unattractive one. (Sorry, but at least in comparison to Peter Davison, Colin Baker was not much of a looker). Also, the Sixth Doctor needed to see a mirror before he knew what he looked like, suggesting that it wasn't much of a choice. And the 5th Doctor's death was a strange one, where he thought he was going to die outright. How did he find time to "choose" his face?
The next very significant example is Romana II. Romana was one of only two Time Lord companions that the Doctor ever had, and since the first, Susan, left before the words "Time Lord" were ever spoken on screen, Romana is more or less the only Time Lord companion. She's also one of the few characters besides the Doctor to regenerate on screen (only one of the Master's regenerations actually happened on screen). Romana seemed to have a very clear ability to choose her regeneration. Rather than explaining it to you, why don't I just show it to you, since someone was kind enough to upload it to YouTube:
A lot of people have suggested that Romana wasted a whole bunch of regenerations in her indecisiveness. However, more recent episodes point to the possibility that this all only counted as one regeneration. The main clue is the 10th Doctor in "The Christmas Invasion" grows a new hand after it's chopped off. Likewise, after Mels regenerated into River, her body could be riddled with bullets, only for her to regenerate them away into the Nazi soldiers. A lot of people have pointed to this to suggest that Romana's several bodies in this sequence only constituted one regeneration, as the regeneration process seems to last more than a single instant. The concerning part is that she seems to be regenerating just for fun. But this scene did air before the 12 regenerations rule was established in "Marwyn Undead." It's a shame that nobody told the writers in the 70's that writers 30-40 years later would be trying to make a real continuity out of all this.
But why did she have so much choice in her regeneration? No other Time Lord has ever shown this ability. The closest example is when Mels regenerated into River Song, she said she had to "concentrate on a dress size." I wrote a fan fiction one time where I said that this was a special ability Time Ladies had that Time Lords did not: the ability to choose one's own appearance in regeneration. Frankly, I think it's about as good of an explanation as any.
But even if the Doctor can choose his appearance, that only explains one of the other Capaldi's in the Whoniverse. If there was one other Capaldi out there, that would explain the 11th Doctor regenerating into a Capaldi Doctor. But why are there two other Capaldi's out there? It seems a lot like the Clara mystery, except it could hardly be the same thing. Somehow, it seems the Doctor has been split across time. I could almost buy that Caecilius was the Doctor undercover. The episode also features Karen Gillan in a pre-Amy role. Imagine an episode in which we find that the 12th Doctor was there undercover, so was Amy, and Captain Jack is there too (he said he was in Pompeii on "Volcano Day").
But John Frobisher is definitely not an undercover Doctor. Frobisher does a lot of things that the Doctor would find despicable. And the murder/suicide of Frobisher pretty much rules him out as an undercover Doctor.
So I guess I've left you with more questions than answers, but I feel like that's my role more than anything: raising the questions that need to be asked. And they're questions we'll be pondering until Capaldi's debut, which won't happen for about a year.