Warning: MAJOR spoilers ahead for Doctor Who season 14, episode 7, “The Legend of Ruby Sunday.”

The true identity of Susan Twist’s Doctor Who character is finally revealed in season 14’s episode, “The Legend of Ruby Sunday,” and the answer is pretty far removed from many of the theories that were popularized by portions of the fan base. Twist’s ongoing presence in Doctor Who‘s Disney era was one of its biggest mysteries, with her first role coming in “Wild Blue Yonder” as Mrs. Merridrew – Isaac Newton’s maid. Now that the secret is out in the open, the speculation can cease. However, the reveal doesn’t immediately answer every question about Twist’s real Doctor Who character.

Susan Twist is quietly one of the most vital members of Doctor Who‘s season 14 cast, appearing in every single episode of Nucti Gatwa’s inaugural run in some form or another. The sheer lack of connection between Twist’s various appearances made it incredibly difficult to solve the mystery without more context with which to work. Thankfully, showrunner and writer Russell T Davies adds the final piece to the puzzle in season 14’s penultimate installment.

Susan Twist’s Real Character In Doctor Who Was Susan Triad

Susan Triad is S. Triad Technology’s leader

“The Legend of Ruby Sunday” establishes Susan Twist’s character as an “ordinary” human named Susan Triad. The episode shows Susan on the verge of releasing free software to the world, the purpose of which is initially unclear. She’s the frontwoman for a tech company called Triad Technology, which Kate Lethbridge-Stewart explains only became “S. Triad Technology” two years earlier.

Triad has been mentioned as early as the 60th-anniversary special, “The Giggle,” where Mel Bush explains to Donna Noble that UNIT utilizes Triad software. There’s also an advertisement for the company on the side of a bus in the Doctor Who 2023 Christmas special, “The Church on Ruby Road.” It’s not clear how long Susan has had ties to Triad, or if the association is only fairly recent. She seems to be of the impression that she’s an unremarkable human, but her existence confuses even the Doctor.

Susan Triad Was An Avatar For The Doctor Who Villain Sutekh

Susan’s actions may not have been entirely her own

“The Legend of Ruby Sunday” also reveals that The One Who Waits is Sutekh, a Doctor Who villain with a lone appearance in the show’s classic era. Sutekh is a godlike entity who has since been retroactively made a member of Doctor Who‘s Pantheon of Gods by Russell T Davies. Susan’s life was being quietly controlled by Sutekh, who had been living within the Doctor’s TARDIS for what appears to be centuries.

Susan’s physical transformation near the end of Doctor Who season 14, episode 7, is a direct result of Sutekh pulling her strings, as are the deadly abilities she demonstrates by turning a man to dust. As an avatar for Sutekh, she is incapable of resisting his commands, spoken or otherwise. It’s very possible that Susan Triad is now gone for good, with Sutekh wiping away everything she ever was.

Why Susan Twist’s Characters Kept Following The Doctor & Ruby

Susan Triad has shown up in many forms throughout Doctor Who season 14

Sutekh is a being of unfathomable power, and while it’s not explained exactly how he was able to pull it off, it’s clear that he is responsible for installing various versions of Susan Traid throughout the timeline of the Fifteenth Doctor and Ruby Sunday. Because the god of death was integrated into the TARDIS, he went wherever the Time Lord and his companion went. His borderline omnipotence allowed him to place Susan Triad into the nearby environment wherever the blue box landed.

The ploy may have been a power play from Sutekh, simply doing it because he could without the Doctor detecting him or even knowing what was going on. Although Gatwa’s Doctor did start to notice Susan’s face following him and Ruby, he didn’t have an explanation for the phenomenon. Instead, he turned to UNIT for help. However, another possibility for Sutekh’s actions could be to keep an eye on the Doctor and Ruby, as it’s unclear how much he can actually perceive from within the TARDIS and whether he can stray all that far from it.

Was Susan Triad Ever A Real Person In Doctor Who?

The S. Triad leader probably pre-dates her role with the tech company

Susan Triad could have been an autonomous figure at some point, or she could have always been an avatar of Sutekh. Again, this isn’t clearly explained in “The Legend of Ruby Sunday,” but a salient theory can be gleaned from “Pyramids of Mars.” In the Tom Baker adventure, Sutekh takes control of a character by the name of Marcus Scarman, who acts very similarly to Susan Triad when under the god of death’s control.

Scarman is an established human character near the beginning of the classic story, and he even has a brother who mourns his death. Baker’s Doctor repeatedly tells Scarman’s brother that Marcus is no longer the man he knows and loves, but it does confirm that Marcus Scarman was just a regular man before his run-in with Sutekh. So, something similar may have happened with Susan Triad. Susan also communicates with Sutekh during their whispering exchange, teasing two distinct personalities fighting for dominance.

There’s no solid evidence for Susan Triad’s existence predating Triad Technology, but Marcus Scarman’s brother essentially proved that the Sutekh avatar in “Pryamids of Mars” went far beyond being a mindless servant of the god of death. However, logic would seem to dictate that Sutekh’s history can be used to inform his present, and the ability to conjure sentient lifeforms out of thin air has never been established as part of his arsenal. In fact, as the god of death, his aim is the exact opposite of bringing life to the universe.

Why The Doctor Thought Susan Triad Was His Granddaughter

Sutekh clearly chose Susan Triad as his avatar to mislead the Doctor

Sutekh seemed to have been intentionally misleading the Doctor by making the Time Lord believe that Susan Triad could be actually an older or regenerated version of Susan Foreman – the Doctor’s biological granddaughter from the show’s classic era. Choosing an avatar with the same first name is an obvious sign of this deception, but the S. Triad/TARDIS anagram is yet another signifier of Sutekh’s manipulation of the Doctor.

Only once Sutekh has successfully lured the Doctor into a trap does the god of death reveal his ruse: “Did you think I was family, Doctor?“ The complex web of lies weaved by Sutekh was seemingly all put in place to mock the Doctor, as well as providing him with the false sense of hope that he might eventually be reunited with his granddaughter. While the Doctor may eventually experience such a reunion at some point in time, this false alarm was nothing more than Sutekh pulling at the heartstrings of Doctor Who‘s main character.