Doctor Who's Christmas special pairs Ncuti Gatwa's Fifteenth Doctor with his second companion, and her story will begin in a way that's very similar to that of Millie Gibson's Ruby Sunday. Bridgerton star Nicola Coughlan will play Joy in "Joy to the World," serving as Gatwa's second companion in less than 12 months. Joy's first adventure with Fifteen mirrors Ruby's in one specific way, as revealed by a recent teaser of the installment.

Between Coughlan's role in the Doctor Who Christmas specials will be the first to feature Coughlan's character, her debut won't be all that original.

Ruby Sunday & Doctor Who's Next Companion Both Visited The Dinosaur Era Soon After Meeting The Doctor

Joy's first Doctor Who episode brings her face-to-face with a T-Rex

Although Ruby's Doctor Who debut, 2023's "The Church on Ruby Road," took place mostly in present-day London, she did eventually travel in the TARDIS in Doctor Who season 14, episode 1, "Space Babies." To prove what the blue box was capable of, the Doctor took them both to prehistoric times, so Ruby could see real-life dinosaurs with her own eyes. The "Joy to the World" teaser confirms that Fifteen also takes Joy to visit dinosaurs - even if he seems to do so almost by accident.

There is a big difference between Ruby's trip to prehistoric times and Joy's journey with the Doctor. After the Doctor fixes Ruby's changes to the timeline by standing on a butterfly, her time with the dinosaurs in Doctor Who has pretty much nothing to do with the larger plot of "Space Babies." Inversely, "Joy to the World" looks as though it's folding Earth's dinosaur era directly into the plot. Still, it's an interesting parallel between both companions' first episode.

Why Ncuti Gatwa's Doctor Is Making More Trips To Prehistoric Times

Disney's financial contributions to Doctor Who opens the door to bigger adventures

With Doctor Who now co-produced by Disney, the long-running BBC sci-fi show has a higher budget than ever. Periods of the show's history, especially Doctor Who's classic era, often had to compromise on the episodes' aesthetic to prioritize the plot. With the show's influx of cash from the Disney+ deal, the Doctor can now explore settings and creatures that would have once been far more restrictive. In short, special effects are expensive, so the CGI dinosaur in the Doctor Who Christmas teaser is evidence that the show is making full use of its new financial advantage.