There are a number of thought-provoking moments from Doctor Who's "The Eaters of Light" that are probably worth probing this week. The theme stressing similarities rather than differences, the heroic sacrifices for the rest of humankind, and the non-issue of Bill's (Pearl Mackie) sexuality in the time of the Romans would all probably lead to deep discussions of the state of the planet and ongoing social issues. However, considering that Season 10 is quickly approaching its final destination (my, how time flies!), it's probably time to focus on the slow-building, season-long arc of everyone's favorite frenemy: Missy.

Although Michelle Gomez hasn't accrued a great deal of screentime this season, Missy's presence has certainly been felt. We've seen the Doctor (Peter Capaldi) spare her life and then promise to guard her body for 1,000 years. We've seen her offer advice to the Doctor to defeat the Monks. And we've seen her help to pilot the TARDIS in order to save the Doctor and Bill from living out the rest of their days on Mars together. Now that she's free from the vault, she's doing maintenance on the TARDIS and putting up a good front in order to win the award for Most Improved. She's even bringing the tears to sell it!

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"I don't even know why I'm crying," she tells the Doctor at the end of this week's uneven hour. "Maybe you're trying to impress me?" he offers in response. "Yes, probably some devious plan. That sounds about right," she replies.

This isn't the first time we've seen an emotional response from Missy this season; in "The Lie of the Land" she tearfully recalls that she has been remembering all the people she has killed. It's these little moments this season that imply the Doctor's former friend may be changing and is, if not completely trustworthy, at least no longer actively trying to destroy him.

Michelle Gomez, <em>Doctor Who</em>Michelle Gomez, Doctor Who

The Doctor and Missy's broken relationship is one that obviously extends back into the reaches of Classic Who and is one of the most complicated relationships in all of the Whoniverse. And it's mostly been the same each time it's been trotted out: The Doctor wants to believe — he hopes — that the Master/Missy has changed or is capable of good, but in the end, he's always disappointed when her psychopathic tendencies resurface and she turns on him. Based on their history together, it makes sense that the Doctor is hesitant to accept that he's not being manipulated.

As viewers, it's equally hard for us to watch this entire scenario play out, because we want to believe people are capable of change, we want to believe that Missy is capable of good and has turned a new leaf. But we've also seen these two clash many times before. The relationship between the Doctor and Missy is so far beyond the point where we should be yelling at the naive girl to break up with her no-good, bad-boy boyfriend because she can't change him. (Yes, apparently the Doctor is the girl in this scenario. Just go with it.) You are smarter than this, Doctor! Do not fall for Missy's wit and good looks! You deserve better!

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And yet, we all know the Doctor won't shirk his duties or turn his back on Missy completely. He's not that kind of man. So we'll sit here pondering all the ways Missy could be playing the Doctor because what else can we do? The questions of why and how the TARDIS returned to Earth last week when Nardole (Matt Lucas) returned to it for supplies still remain as we look forward to next week, which will see Missy attempting to be a hero — or at least not completely evil. (Jessica Jones tried this already, so we'll see what happens when Doctor Who attempts it.) Was it all Missy's doing so that Nardole would be forced to come to her for help and thus free her from the vault? Was it a strange whim of the TARDIS that brought him back? The end of the season is in sight, so I guess we'll find out soon enough.

But if it turns out that Missy is the one responsible for the Doctor's regeneration, we're going to have to fight.

Doctor Who airs Saturdays at 9/8c on BBC America.