One of The Doctor’s biggest nemeses is back for Doctor Who Season 12. How is it possible? Here are our theories on the future episodes.

Caution: There are MAJOR spoilers in this post for the Doctor Who Season 12 premiere. I urge you to check out the episode first and then read this post! If you read on without watching, don’t complain to me that the big twist has been ruined.

Hands up if you saw that big twist coming at the end of the Doctor Who Season 12 premiere. Chances are unless somewhere like The Daily Express, ScreenRant or other publications that just didn’t think (and only wanted the clicks) spoiled it for you, there’s no way that you would have seen it coming. That’s despite there being multiple clues as to this major return.

And I do mean major. Are you ready for the spoilers?

The Master is back. It turned out that O in MI6 has always been The Master. Before O went to work at MI6, The Master shrunk the character and became that person. Yep, really! So, The Master has been ready for The Doctor to come to him for help.

For many, the big question is how it was even possible. Didn’t John Simm’s Master and Michelle Gomez’s Missy kill each other? Didn’t they bring some sort of end to the regeneration cycle in Doctor Who during Peter Capaldi’s era?

Well…sort of…

C’mon, this is The Master! He can do anything, right? He’s cheated death before. We’ve seen him choose not to regenerate and then get brought back.

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But is this a regeneration after Missy?

Let’s be honest; this is Doctor Who and there’s a lot of timey-wimey stuff. There’s no guarantee that this is The Master after Missy. This could be a regeneration before her; before Simm. We’ve only seen a handful of The Master’s regenerations, so there is a chance that with the right planning and timeline, this is one of the earlier options.

The doesn’t quite fit the timeline of The Master heading to MI6 to take over O’s body. However, it’s worth noting that The Master from the past could have time traveled, realized the opportunity, and stayed.

Doctor Who: The Complete Eleventh Series (DVD)

A Master from another world?

There’s a HUGE possibility that this is actually The Master from another timeline. Thirteen translated the code and found that there are images of multiple Earths. All these Earths are being infected by this new alien. And that opens the doorway to The Master as O not being from our world; from The Doctor’s world.

We all know parallel dimensions exist. They’ve been looked at in earlier seasons, such as during Eccelston’s and Tennant’s eras. He literally left Rose in another world with her mom and the father from that world. It was surprising to see that Thirteen couldn’t work out why there were multiple Earths. She should know considering she is Ten.

But I digress. The multiple Earths open the possibility that this isn’t our Master. O is a Master from another dimension. And that’s going to cause some major headache, like all time travel does.

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What do you think the multiple Earths mean? How is The Master back in Doctor Who Season 12? Share your thoughts in the comments below.

Doctor Who Season 12 continues on Sunday, Jan. 5 at 8/7c on BBC America/CTV Sci-Fi Channel.