Following Varada Sethu’s first appearance as Munday Flynn in the Doctor Who episode “Boom,” questions began to form about how the actress would return in season 15. Varada Sethu’s unexpected debut in Doctor Who is a shock yet exciting. The actress isn’t meant to join the Doctor Who season 14 cast at all, with many believing that she wouldn’t appear in the show until the following season.

In “Boom,” the Fifteenth Doctor (Ncuti Gatwa) and Ruby Sunday (Millie Gibson) meet Mundy Flynn in a high-stakes, tension-filled adventure. However, the three do not know each other yet, or at least Doctor Who is letting people believe. Varada Sethu’s sudden arrival in one of Steven Moffat’s best Doctor Who episodes has made her role in future installments of Doctor Who ambiguous yet exciting. However, how the actress will fit into season 15 is still unknown, especially following the implication that Varada Sethu may be portraying a new character.

10

Varada Sethu’s New Doctor Who Companion Is Mundy Flynn’s Ancestor

The Actress May Be Following The Same Process As Previous Doctor Who Stars

In Doctor Who, future companions are famously included in other roles before their debut as main characters. For example, Martha Jones actress Freema Aygeman portrays Adeola in the season 2 episode “Army of Ghosts.” Adeola works for Torchwood and sadly dies at the hands of the Cybermen. When Martha is introduced in the season 3 episode “Smith and Jones,” she tells the Tenth Doctor (David Tennant) about her cousin, who turns out to be Adeola.

The same happens with Amy Pond actress Karen Gillan, who plays a member of the Sibylline Sisterhood in the season 4 episode “The Fires of Pompeii.” However, there is no connection between the two characters. As Doctor Who often brings in performers to play ancestors of companions, it wouldn’t be a surprise to discover that Sethu’s new character is a relation of Mundy Flynn. With time travel involved, anything could be possible, especially with season 14’s recurrent themes of family.

9

Varada Sethu’s Doctor Who Return Is Connected To Susan Twist

There’s Always A Twist At The End

Doctor Who season 14’s Susan Twist theories are growing massively, as she is appearing in every episode in various roles. In “Boom,” Twist is the interface of the ambulance system, for example. She also appears in the 60th-anniversary special “Wild Blue Yonder” and the Christmas special “The Church on Ruby Road.” One theory suggests that Twist is multiple different characters with the same face, spread out across time and space and following the Doctor, much like the words “Bad Wolf” did.

If this theory is correct, there’s a chance that Sethu’s character is going through the same experience. Sethu’s season 15 character may not be Mundy Flynn but someone who happens to have the same face. This could explain how Sethu’s character boards the TARDIS in season 15 after the Doctor and Ruby recognize her as Mundy and take an interest in why she doesn’t remember them from “Boom.”

8

Mundy Wasn’t A Real Person In Doctor Who Season 14

Boom Might Have Set Up Mundy Flynn As A Hologram

“Boom” sets up a fascinating concept in the Doctor Who universe: the dead are immediately converted into holograms from Villengard’s programming. After dying, the deceased can still be interacted with through an AI recreation of their personality. Doctor Who previously features holograms that are so similar to reality that even the Doctor struggles to decipher if they are real or not, which creates doubt over whether Mundy Flynn is actually alive in “Boom.”

It’s unlikely that the mystery surrounding Mundy Flynn’s connection to Sethu’s season 15 character will be resolved in season 14, which sets up the possibility of a multi-season story arc. If the Villengard is seeking revenge on the Doctor across time, much like the Silence throughout Doctor Who seasons 5 and 6, then perhaps the appearance of Sethu’s character is being used to lure the Doctor into danger, and she isn’t aware that she’s not flesh and bone either.

7

Varada Sethu Is Playing Another “Impossible Girl” Like Clara

Doctor Who Might Be Borrowing From Previous Storylines

The season 7 episode “Asylum of the Daleks” notably debuts Jenna Colman in Doctor Who as Oswin Oswald. However, she later returns to the show as Clara Oswald, Colman’s primary character in the show. By the end of season 7, the Eleventh Doctor (Matt Smith) discovers that she is split across time using variations of her name, but all of Clara’s versions in Doctor Who are seeking out all of his to offer help. The storyline of “The Impossible Girl” is a vital part of Clara’s tenure, and there are suggestions that Doctor Who is replicating this for Sethu’s character.

In an interview with the Hollywood Reporter, Steven Moffat confirms that he and Russell T. Davies are “do[ing] Clara again” while acknowledging Sethu’s first appearance in “Boom” (via Hollywood Reporter). Although it will not make any sense for Doctor Who to recreate Clara’s storyline for Sethu in the exact same way, it raises queries about how the character is connected to the Doctor and Ruby in their futures, such as whether she is seeking them out with a purpose, or what her season 15 incarnation is in relation to Mundy.

6

Varada Sethu’s Doctor Who Season 15 Character Will Pay Off That “Mundy Sunday” Tease

Sethu’s Character Could Be Ruby Sunday’s One True Love

The Fifteenth Doctor makes a joke in “Boom” about Mundy and Ruby marrying, stating that he’ll find it hilarious to call her “Mundy Sunday.” Doctor Who, but especially Moffat, doesn’t include these details for no good reason, and it implies that the two women will have a relationship in the future. Doctor Who has already confirmed that Ruby Sunday is bisexual, and Mundy never corrects the Doctor in his statement, so there may be some truth to it.

Assuming that Mundy, or another character of Sethu’s in season 15, is Ruby’s future wife, this will be the second time that the Doctor travels with an engaged or married couple. The first is Amy and Rory (Arthur Darvill), who marry in the season 5 finale, “The Big Bang,” and continue on adventures aboard the TARDIS until their departure in season 7. While the future of Sethu’s character and Ruby Sunday is unclear currently, it seems too much of a coincidence that this offhand remark isn’t a reference to a relationship between them.

5

Varada Sethu’s Character Is Connected To Mrs. Flood

Ruby’s Enigmatic Neighbor Has Something To Hide

In “The Church on Ruby Road,” Ruby’s neighbor, Mrs. Flood (Anita Dobson), is first seen. Several concepts are being created about who the woman truly is, and even Ncuti Gatwa shared his Mrs. Flood theory recently. However, Mrs. Flood is yet to appear in Doctor Who season 14. There is a possibility that Mrs. Flood’s involvement with Ruby is actually because of Sethu’s character instead. For example, if Sethu’s character is out of sync with the Doctor and Ruby, she may be using Mrs. Flood to try and line herself back up with their timeline.

But it could be the other way around. Mrs. Flood might be seeking out Sethu’s character instead and is keeping tabs on Ruby until she appears. There is also a slim chance that the two are connected in a way that doesn’t involve the Doctor or Ruby at all, and the pair simply get caught up in a feud or battle that has nothing to do with them. Mrs. Flood is a mysterious figure, and so is Sethu’s future character at this time, so it makes sense that the two share ties somehow.

4

Varada Sethu’s Character Is One Of Carla’s Former Foster Children

Ruby Sunday Has 33 Foster Siblings, And Sethu’s Character Could Be One Of Them

The Doctor Who 2023 Christmas special also explains that Ruby’s mother, Carla (Michelle Greenidge), fostered 33 children before and after her daughter. Carla also claims that she still keeps in touch with a few of them, so maybe Sethu’s character is one of them. If she is older than Ruby, the Doctor’s companion may not remember her, especially if Sethu’s character didn’t stay with them for very long. Or, she may have also been fostered by Carla before Ruby’s birth.

With the new era of Doctor Who focusing on the topic of adoption frequently, both with the Doctor and Ruby, it wouldn’t be surprising to discover that Sethu’s character has a prior connection to Carla’s foster children. In one scene in “The Church on Ruby Road,” time is altered, and all of Carla’s former foster kids disappear from the photographs she has. Perhaps Sethu’s character is one of them, but the brief change in timeline creates a copy or alternative version of her that becomes Mundy Flynn.

3

Varada Sethu’s Character Is Sent By River Song To Keep An Eye On The Doctor

The Doctor’s Wife Is Always Watching

In a recent interview with Collider, Alex Kingston spoke about wanting to see her character River Song cross paths with Ncuti Gatwa’s Fifteenth Doctor (via Collider). Because of Moffat’s return with “Boom” and the confirmation that he is writing the 2024 Christmas special, it seems more likely than ever that Doctor Who’s River Song might meet the latest incarnation of her husband. River’s most recent appearance in the show is in the Twelfth Doctor (Peter Capaldi) episode “The Husbands of River Song.” However, the character is still prominent in Big Finish audio dramas and other Doctor Who stories.

“Boom” also establishes that Mundy Flynn is a member of the Anglican Church. The church is first introduced in the season 5 episode “The Time of Angels,” when River works alongside them against the Weeping Angels. Although it’s not clear exactly when these two episodes occur timeline-wise, Moffat deciding to include the Anglicans in “Boom” could be a tease about River’s return. River always keeps tabs on every incarnation of the Doctor, so perhaps she sends Mundy or Sethu’s character to keep a close eye on the Time Lord as she prepares to make a sudden reappearance in his life.

2

Varada Sethu’s Character Is A Future Ruby Sunday

The Pair Could Be The Same Gallifreyan At Different Points In Their Timeline

While the mystery surrounding Ruby Sunday’s true identity and parentage is still playing out, one Doctor Who theory suggests Sethu is a regeneration of Ruby from the future. Although Millie Gibson is supposedly reprising her role as Ruby in Doctor Who season 15, it has been implied that her time aboard the TARDIS isn’t as prominent. The episode “The Giggle” also set up the return of the Master, so it’s known that more Time Lords are likely to appear in season 14.

If Ruby is a Time Lord, either one that has appeared in Doctor Who before or a new character, Sethu could be the same person. In “Boom,” Ruby and Mundy Flynn never touch, and if they are the same person, it’s good that they don’t, as it would create a paradox. Other Doctors share adventures frequently, so there is no reason why Ruby/Mundy can’t do the same. The only criticism of this theory is that the Doctor can usually sense other Time Lords around him. However, this isn’t exclusive, and his species has ways of hiding themselves when needed.

1

Varada Sethu’s Character Is The Rani

The Doctor Didn’t Just Grow Up With The Master

Since showrunner Russell T. Davies first rebooted Doctor Who in 2005, he has faced hundreds of queries from audiences about whether the famous Time Lord, the Rani (Kate O’Mara), will ever return. The Rani is a genius, much like the Doctor, who is a core villain in several classic Doctor Who serials. She is a childhood friend of the Doctor and the Master and grew up with them on Gallifrey, but she teeters somewhere between the two morally and is neither inherently evil nor good.

Davies has often mentioned the Rani in relation to Doctor Who. For example, in an interview, he states that his ideal casting choice for the Rani is Ruthie Henshall (via Games Radar). In the DVD commentary for “Last of the Time Lords,” he also jokes that the Rani is the hand that takes the Master’s ring from the ashes. However, this last comment is interesting. “The Giggle” sees a mystery person take the gold tooth from the Toymaker (Neil Patrick Harris) that contains the Master after his banishment, so maybe Davies is bringing back the Rani through Varada Sethu’s character.