Doctor Who has been turning out a terrific Season 10 (or Season 36 for those of us who keep it old-school). But with rumors that there’s going to be a new Doctor, we know it won’t be ending well for Capaldi’s incarnation. We don’t know exactly what’s in store. But we have a theory, thanks to Reddit.
As we know, the Doctor had been rendered blind in “Oxygen” and had saved Missy from execution in “Extremis.” Redditor Absolutedisgrace believes these two events are connected:
When the doctor stopped Missy's execution, he couldn't prevent the death due to too many safe guards. It needed to kill a timelord. Instead, he channelled as much as needed to save her, but not enough to die outright either. He has been dying this entire series. He couldn't restore his eyesight with regeneration energy, because he can't actually regenerate. He said it was "forever" because he knew he wasn't regenerating when he 'dies' this time.
This is why the Doctor has been teaching people this whole series. He genuinely thinks his real end is near. He wants and is trying to change Missy as he believes she is going to have to take his place.
This theory works for me. The Doctor has experienced physical injury on one other occasion—when he lost his hand in “The Christmas Invasion”; Captain Jack later found it and used it to detect the Doctor when he returned to Cardiff. Given this, the Doctor’s current blindness is likely related to the plot.
Missy may even have an inkling that something about the Doctor isn’t shipshape. In the most recent episode, “The Empress of Mars,” Missy looked at the Doctor and without preamble asked, “Are you all right?”
Because this is Doctor Who and not The Adventures of Some Time Lord or Other, Absolutedisgrace suggests that the Doctor won’t die a permadeath. But in order for this to happen, Missy will redeem herself for her many crimes and sacrifice herself so that the Doctor may live. It’s a nifty theory and poignant as hell. (Plus, it doesn't elicit guffaws, like this theory about Jar Jar Binks being a Sith lord.)
What do you think is in store for the good Doctor?