Following the introduction of Varada Sethu’s Belinda Chandra in Doctor Who season 15’s ending are also forming, too, but considering Varada Sethu’s appearance as Mundy Flynn in season 14’s “Boom,” audiences are more focused on what the link between the new companion and the Time Lord is.

Viewers will be looking closely at all the new characters in Doctor Who season 15, and try to figure out the answers to questions such as: Who tells the Doctor about Belinda? How do the Robots get her Star Certificate? And, most importantly–what is the connection between Mundy and Belinda? As we wait for Doctor Who to explain, these theories about Belinda and the Doctor are worth pondering.

7 Belinda & Mundy Are Two Regenerations Of The Same Time Lord

Is Doctor Who Repeating The Tenth & Fourteenth Doctors' Fate?

While every incarnation of the Doctor in Doctor Who typically looks rather different from the last and next, Russell T Davies has already proved that the rules of regeneration aren’t set in stone. There’s a chance that Belinda and Mundy are the same Time Lord, although whether Mundy is aware of this is unclear, but it’s obvious that Belinda is none the wiser. If the Fourteenth Doctor can return to a previous appearance, why couldn’t Belinda/Mundy?

Although Doctor Who previously established that Time Lords can typically sense each other out, this isn’t an exclusive rule, like in the two-part episode “Spyfall,” for example.

In fact, could Belinda/Mundy be the first socialite Gallifreyan to reuse the same body again and again? Although Doctor Who previously established that Time Lords can typically sense each other out, this isn’t an exclusive rule, like in the two-part episode “Spyfall,” for example. Perhaps Belinda is living out a pocket watch situation like the Master, and that’s why the TARDIS can’t take her home. Maybe she’s dangerous, and the Doctor’s ship is trying to avoid bringing her back to Earth, as she’s the cause of the heavily implied destruction of Earth at the end of “The Robot Revolution.”

6 Belinda Saves Earth At The End Of Season 15 (& The Doctor Needs Her)

Is Belinda's Fate Set In Stone?

The imagery of the London black cab, the Eiffel Tower, and the Statue of Liberty floating through space in “The Robot Revolution” is haunting, but it’s apparent that the date of May 24, 2025, is connected to Belinda in some way. One theory suggests that Belinda is the savior of Earth, stopping the harrowing events from occurring in the first place. But will she have a happy ending? While we don’t know exactly what events result in the fragments of humanity floating across space, it’s obviously fatal.

Belinda proves in “The Robot Revolution” that looking after others is her number one priority, and I think it’s likely we’ll see several more moments that demonstrate this in future episodes. Perhaps this core quality of Belinda’s will also be her downfall, though. However, she could also survive, but I can’t help but feel that the latest episode is hinting towards an unfair fate for the new companion as well. Belinda is labeled the Queen of Earth at the end of “The Robot Revolution,” and I suspect this title could be more official than Doctor Who is currently letting on.

5 Belinda Is Ruby's Danny Pink

Did "Boom" Set Up Ruby's Future Relationship?

When Ruby Sunday meets Mundy Flynn in season 14’s “Boom,” one of Steven Moffat’s best Doctor Who episodes, there is a joke about the two women marrying one day and Mundy becoming “Mundy Sunday.” While this has been an obvious theory since the release of “Boom,” the recent introduction of Belinda in “The Robot Revolution” is making me suspect that there still could be something in this connection. Perhaps nothing is supposed to happen between Ruby and Mundy, but it doesn’t mean that the season 14 companion can’t be destined for Belinda instead.

The Twelfth Doctor and Clara Oswald famously cross paths with Orson Pink, Danny’s ancestor, and maybe this could be the same for Ruby, Belinda, and Mundy, but backwards. Maybe when the Doctor finally reconnects with Ruby and introduces Belinda, the memory of Mundy will cause something to click. This doesn’t necessarily mean that Belinda will face the same fate as Danny Pink, though, and if anything, I hope a Doctor Who companion actually gets a happy ending with their beloved without death or separation being involved, as it’s been a while since audiences have been treated to such a storyline.

4 Belinda Is Mundy Flynn

What If Belinda Doesn't Get Home?

Doctor Who season 15’s marketing materials are rife with the phrase “Get her home,” which is clearly what the overarching story arc will be. Of course, the end of “The Robot Revolution” shows the Doctor being unable to take Belinda back to Earth on May 24 2025. While many naturally assume that the end of the season will see the new companion finally make it back to her home planet, perhaps this won’t be the case.

What if the connection between Mundy and Belinda is as simple as them being the same person? The Doctor tells Belinda about Mundy in “The Robot Revolution,” but just because the Time Lord refers to the “Boom” character as an ancestor, this doesn’t necessarily mean it’s true. Perhaps Belinda is forced to take on the role of Mundy so that she can live out the events of “Boom” and save the Doctor and Ruby, which ensures that she and the Time Lord eventually meet, too. Whether Belinda gets home after this, however, is yet to be discovered.

3 Belinda Really Is The Queen Of Earth

Is The New Companion Actually Earth's Monarch, And Is Simply Unaware?

During the ending of Doctor Who’s “The Robot Revolution,” Belinda is given the new title of “Queen of Earth” by Manny and the other rebels of MissBelindaChandra. While this initially seems more like a term of endearment or simply a thanks for Belinda’s attempted sacrifice, perhaps there is more weight to Belinda’s new label than it seems. What if Belinda really is the Queen of Earth, and just doesn’t know? Stranger things have happened in the world of Doctor Who, and this wouldn’t be the first time a companion discovered they had a bigger role in the universe.

Timelines are complicated, so maybe Belinda isn’t actually Queen of Earth yet, and Manny’s comment is foreshadowing her future. Like Rose Tyler in “The Christmas Invasion” or Martha Jones back in season 3, it’s possible that Belinda is forced into a situation where she has to slip into the Doctor’s shoes to save the Earth because the Time Lord is incapacitated. Belinda’s Star Certificate is sent 5000 years into the past, and it becomes a major part of MissBelindaChandra’s societal myths, so there’s also a chance that she’s always been queen, too.

2 The Master Is Pulling The Strings Of Belinda's Story

Maybe Russell T Davies Isn't The Only One Making References To Past Doctor Who Eras

“The Giggle” establishes that the Master will make a return at some point soon, and I can’t help but shake the idea that the villainous Time Lord is behind Belinda and the Doctor meeting. The Master has pushed a companion and the Doctor together before, so why not again? There are several details in “The Robot Revolution” that make me believe the Master is recreating moments from Davies’ original era: Belinda’s flatmates calling her Linda, a reference to “Love and Monsters,” and the Star Certificate being ed on April 5, 2008 (the date “Partners in Crime” aired), for example.

However, I think there’s a focus on the Saxon Master arc. The parallels between Belinda and Martha are immediately clear, but it’s more than them both working in the medical field. Martha’s cousin dies in season 2, and Freema Agyeman plays both characters, much like Belinda and Mundy. Plus, Eve Myles as Gwyneth and Gwen Cooper, too. Belinda’s neighbor is called Lucy, which may be a small nod to Harold Saxon’s late wife of the same name as well. With the show leaning into more meta territory, my theory is that the Master is actively retconning Doctor Who’s Timeless Child.

Wanting things to go back to how they were before, I think the Master is littering these parallels between the current era and Davies’ original tenure as hints for the Doctor.

The Master is in the Toymaker’s gold tooth, but what if he has the ability to alter reality like the rest of the Pantheon now? Sacha Dhawan’s unhinged Master makes it clear that he is bitterly jealous and angry about the Timeless Child, and if he had the chance to change that, wouldn’t he take it? Wanting things to go back to how they were before, I think the Master is littering these parallels between the current era and Davies’ original tenure as hints for the Doctor.

1 Belinda Is Rani Chandra's Daughter

Despite The Plot Holes, Does The Sarah Jane Adventures' Canon Tease Belinda's Existence?

Doctor Who audiences know that the writers can’t always be trusted, and just because Davies has debunked the theory that The Sarah Jane Adventures’ Rani Chandra is not related to Belinda (via The Direct), I don’t necessarily trust him. There are a few details about Rani that link her to Belinda, and while they may be a bit of a stretch, there’s no doubt that they’re interesting to ponder and shouldn’t be ruled out as of yet.

In The Sarah Jane Adventures episode “The Mad Woman in the Attic,” it’s established that Sarah Jane leaves her house to Rani after her death. The story initially follows a timeline in which Rani is essentially a hermit, but when time changes, she has a big happy family. In her happy ending, she has a son, but what if hermit Rani has a daughter at a young age? With the time rupture in “The Robot Revolution,” perhaps this timeline and the current one blur together, which would explain the fact Rani should be in her 30s in 2025.

Maybe Belinda is adopted, too, and is completely unaware of Rani’s existence. Plus, Rani is grounded to Earth by the Judoon in The Sarah Jane Adventures episode “Prisoner of the Judoon.” Assuming Clyde Langer is her father (and I refuse to believe anything different), it would make sense that any of his and Rani’s children would also be grounded. As Belinda is kidnapped, she’s able to leave Earth, but the grounding is what causes the interference with the Doctor getting her back home.

If Doctor Who’s Belinda is Rani’s daughter, but from a timeline that doesn’t technically exist anymore, couldn’t Davies argue that they aren’t related, as Belinda isn’t birthed by the legit version of Rani? While this is more of a connection to The Sarah Jane Adventures than the Doctor, it’s also well-known that Sarah Jane held a big space in the Time Lord’s hearts, as did her chosen family and children.