Returning Doctor Who companion Bill Potts may not be all that she seems in the 2017 Christmas special episode, "Twice Upon A Time". This year's festive adventure will act as the final bow for Peter Capaldi's Twelfth Doctor, paving the way for Jodie Whittaker's debut as the iconic Time Lord. Intriguingly, "Twice Upon A Time" will be a multi-Doctor affair, with actor David Bradley taking over from the late William Hartnell as the very first incarnation of the Doctor.
Also appearing in the episode is the Doctor's most recent companion, Bill Potts, who was far from a guaranteed addition considering her eventual fate in the season ten finale. The last time Doctor Who fans saw Bill, she had been converted into a Cyberman but was saved from a grim, metallic fate by her former crush, Heather, who transformed Bill into some kind of omnipotent, sentient puddle (sci-fi, eh?). Although the season ended with Bill and Heather setting off to travel the universe together, the groundwork was laid for Bill to one day return to her human form.
Related: Doctor Who Christmas Special Left 'Everyone in Tears'
Many viewers might assume that this is exactly how Bill winds up by the Doctor's side in "Twice Upon A Time" but actress Pearl Mackie suggests that her character's return may not be all that straightforward. As reported by Radio Times, Mackie said:
“It was a total honor to be asked back and it’s even more exciting that it’s for a Christmas special! Bill is 100% back with the full Bill energy but she’s not quite all she seems… There’s so much [going on in the episode]. We’ve got not one but two TARDISes and we travel in both of them which is pretty exciting.”
Mackie's comments seem to suggest that Bill hasn't suffered any lingering problems as a result of turning from a human to a Cyberman to an oil creature and (possibly) back into a human but equally, it doesn't sound like Bill will simply be returning to her traditional companion role. Although it may be a stretch to suggest that Bill could have villainous intentions when she reappears this Christmas, it's highly feasible that traveling the universe with Heather has fundamentally changed the character. Perhaps Bill will return as a wiser and more powerful liquid entity and play a role similar to that Rose Tyler took on as The Moment in "The Day Of The Doctor".
However Bill finds her way back to the TARDIS, it seems very likely that "Twice Upon A Time" will be the character's final appearance in Doctor Who, at least for the foreseeable future. Although Pearl Mackie's companion was undoubtedly a popular one, incoming showrunner Chris Chibnall has already cast a trio of new faces to run away from monsters alongside Jodie Whittaker next season.
MORE: Why The Doctor Wanted to Become a Woman
Doctor Who returns with "Twice Upon A Time" on Monday, December 25, on BBC and BBC America.
Source: Radio Times