Warning: Spoilers ahead for Doctor Who season 15, episode 4, "Lucky Day."Doctor Who​​​​​​'s new UNIT team. Although the adjusted formula makes for a great installment, it highlights what was said before the 2025 premiere.

Gibson filled the position in the Doctor Who season 14 cast that is now held by Sethu. This isn't anything particularly new, as companions rarely last more than a single season when Doctor Who is under the stewardship of returning showrunner Russell T. Davies. While other showrunners haven't been afraid to give the Doctor more than one companion at the same time, it's something that Davies largely tends to avoid. Instead, he tends to stick to the more time-honored tradition of the Doctor traveling with a lone companion. For season 15, it was implied he would shake things up.

Doctor Who Made It Seem Like Belinda & Ruby Would Both Be Companions In Season 15

Belinda & Ruby have shared an episode, but not the screen

Speaking with Doctor Who just before season 15 began with "The Robot Revolution," both Sethu and Davies commented on what the coming episodes would look like when it came to who would be physically present within the TARDIS with Gatwa's Doctor. While it was widely understood that Ruby would be taking a step back from the show, the announcement of her role within Doctor Who season 15's cast led many to believe that both she and Belinda would serve as simultaneous companions for the second season on Disney+.

Belinda is relegated to a ing role (if that) while Ruby becomes the main character in her 2025 Doctor Who comeback.

Specifically, Sethu said, "I couldn't ask for a better team than Ncuti and Millie to be on this adventure with." By the end of Doctor Who season 15, episode 4, "Lucky Day," Sethu and Gibson have yet to share the screen. They both appear within the runtime of "Lucky Day," but Sethu only has one scene right near the beginning, and she doesn't interact with Gibson's character at all. Instead, Belinda is relegated to a ing role (if that) while Ruby becomes the main character in her 2025 Doctor Who comeback.

Granted, Sethu's words could be interpreted in a number of ways, with one generous reading potentially being that Gibson was simply offering Sethu advice on what it takes to be a star on Doctor Who. When Davies' comments on the matter are taken into , it becomes tougher to ignore the strong implication that Ruby and Belinda were pushed as a companion duo rather than one replacing the other. The showrunner explained, "We've got Ncuti, Millie, and Varada fighting side by side - we need all three, because the stakes are higher than ever!”

It Doesn't Look Like Ruby Sunday Will Be ing The Doctor & Belinda In The TARDIS

Ruby is making an effort to leave the Doctor behind

Doctor Who season 15's focus so far has been the struggles of getting Belinda back to May 24. The TARDIS' inability to get Belinda home is what causes her adventures as she and Fifteen take "the long way round." After the opening scene of "Lucky Day," Belinda's arc stops being relevant to episode 4's story. Instead, what we get is a break from the main storyline to see how Ruby is settling back into life on Earth after her action-packed adventures with the Doctor. Belinda wouldn't fit into that story, and Ruby, so far, has no place in Belinda's.

It seems that "Lucky Day" was more of a welcome break from the action rather than a way for Ruby to reenter the main arc.

Plus, with Ruby back on Earth, and Earth proving to have been destroyed at the end of "The Robot Revolution," Gibson's character is either a victim already or in desperate need of saving along with the rest of humanity, depending on how her scenario is viewed. So, while I wouldn't rule out another appearance from Ruby before the end of Doctor Who season 15, it seems that "Lucky Day" was more of a welcome break from the action rather than a way for Ruby to reenter the main arc.

"Lucky Day" is Ruby's first Doctor Who appearance since her brief cameo in 2024's "Joy to the World."

Furthermore, "Lucky Day" and what it did to Ruby could have gone one of two ways. The first option is that what she endured brought her back to the fight to stand shoulder-to-shoulder with UNIT. The second was that it made her realize she needed more time away from all the drama, and that is exactly what happened. She even ends "Lucky Day" by telling Kate Stewart (Jemma Redgrave) that she's going to leave and spend some time alone to reset. Those aren't the actions of someone who is destined to jump aboard the TARDIS again anytime soon.

Belinda Is Great, But "Lucky Day" Proves Ruby Sunday Is Still A Brilliant Doctor Who Character

Millie Gibson's character now has more depth since leaving the TARDIS

Even without the mystery of end of Doctor Who season 14 may have come too soon.

Seeing her getting along so well with Fifteen was a joy in Doctor Who season 14, but she also seemed to take far too much in her stride at the time.

Then again, it may have taken Ruby leaving the TARDIS to deepen her character. Seeing her getting along so well with Fifteen was a joy in Doctor Who season 14, but she also seemed to take far too much in her stride at the time, and her lack of even the slightest amount of friction with Gatwa's character led to their dynamic becoming a little one-dimensional. They were really good friends, which is nice, but it didn't make everything they did together all that entertaining.

Now, with Ruby struggling so badly and trying to move on from the trauma she went through during her time as Fifteen's companion, Gibson's character is far more interesting. Seeing who she was and who she has become is just what Doctor Who needs at the moment, and I hope "Lucky Day" isn't the last time she shows up. Until then, if it ever happens, at least Doctor Who has a great replacement in the form of Belinda Chandra - and whoever may follow her.

Source: Doctor Who