The Time Lord know as the Mistress may have hatched her most nefarious scheme yet: making Doctor Who fans believe she’s turning away from the Gallifreyan dark side and becoming a hero. But if Missy is actually joining the good guys, does that mean she’ll be fighting against her former self; the Master?

Spoilers ahead for Doctor Who season 10 episode 10, “Eaters of Light.”

The latest episode this season found Bill, Nardole and the Doctor uniting ancient Celtic barbarians and Roman soldiers in an epic battle against monsters with neon tentacles who were both allergic to light and ate it. Through some rousing speeches and the power of the TARDIS translation circuit, both Bill and the Doctor convinced the barbarians and Romans to work together. On the heels of previous episode, “Empress of Mars,” this season of Doctor Who has now been extra-critical of earthly Empires, whether they be Roman or British.

While the adventure of “Eaters of Light” was solid and Bill still charming as hell, the big news for hardcore fans was the coda of the episode. Missy has been hanging out in the TARDIS the entire time, and this time, the Doctor has allowed it. After saving everybody in “Empress of Mars,” the Doctor is seemingly giving Missy a trial run at being on the team of do-gooders.

In the final scenes of the episode, both the Doctor and Missy talk tenuously about their new alliance, with the Doctor admitting to his unrelenting optimism, specifically regarding Missy. The performances from Peter Capaldi and Michelle Gomez are spectacular, so much so that it gives a fan pause: could this be real? Could Missy actually be seeing the error of her ways? If true, this turn could represent a welcome change for Doctor Who. Instead of the Master/Missy always screwing-over the Doctor at all costs, the character might have finally become a little more interesting.

This isn’t to say there haven’t been sympathetic versions of the Master before. There have. But the Missy/12th Doctor relationship is definitely something new insofar as you really believe they were friends way back when. And while a lot of the Doctor’s sympathy for Missy has been big this particular season, some of this affection began in season 9, when Missy and Clara teamed-up to find the Doctor when he went AWOL. Back then, Clara also wondered if Missy would stop being bad, a point which the evil Time Lady protested at the time saying dismissively “No. I haven’t turned good.

Actress Michelle Gomez recently told Inverse that she believes that Missy’s attitude toward morality is “something that she might like to try on, or achieve,” meaning this change of heart could be only temporary. Plus, since before the new season began, the Doctor Who faithful have been aware that the previous version of Missy/the Master, would be returning in the form of John Simm at some point in the season. And, in the latest trailer for the next episode, he does in fact make an menacing appearance, complete with a classic Master-goatee.

So, if Missy has turned good, will she battle her former-self in an effort to protect the Doctor and his companions? Or, has this been her plan all along: a kind of universe-dominating-team-up with her last incarnation? And how do the old-school Cybermen fight into all of it? The beginning of the two-part season finale of Doctor Who, season 10, “World Enough and Time,” materializes next week.

Doctor Who airs on Saturdays at 9pm EST on BBC America.

See also: Here’s When Christopher Eccleston Says He’ll Return to Doctor Who

Photos via BBC America