Doctor Who’s Surprise Cameo Teases Big Timeline Gaps
Not every Doctor’s story is complete.

In what turned out to be the very pivotal episode of the 15th Doctor (Ncuti Gatwa), Doctor Who also brought back another incarnation of the titular Time Lord. Yes, “The Reality War” was secretly a multi-Doctor episode, and not in the way we thought at all. But, with the appearance of a previous Doctor alongside our current Doctor, this was about more than just (very recent) nostalgia. With its surprise multi-Doctor moment, “The Reality War” reminded us of one essential truth about the Doctor Who timeline: we’re only seeing a fraction of each Doctor’s life.
Spoilers ahead for Doctor Who’s “The Reality War.”
When Jodie Whittaker’s 13th Doctor strode into the TARDIS toward the end of “The Reality War,” it was perhaps the best-kept secret of the entire episode. While it’s been less than three years since Whittaker’s final episode in 2022’s “The Power of the Doctor,” it feels like more time has passed in the world of Who, partly because so much has happened. And, basically, the appearance of 13 to both comfort and assist 15 in this moment was a reminder of one huge truth: Most Doctors' stories are only partially complete.
The 15th Doctor (Ncuti Gatwa) meets the 13th Doctor (Jodie Whittaker).
From a plot point, the appearance of the 13th Doctor is explained hastily. She’s “popped” over from her own timestream to be with 15 in this moment. Whether or not she’ll remember this when she returns to her own time is unclear. When the Doctor says he loves her (AKA his former self), she is surprised responding, “I never say things like that.” And then, she contemplates telling Yaz (Mandip Gill) that she loves her. For fans of the 13th Doctor era, this was something of a band-aid, as the relationship between Yaz and the Doctor wasn’t explored as much as many fans expected or wanted.
13’s appearance in “The Reality War” doesn’t retcon any of her era relative to Yaz, and yet, it does in the sense that we’re reminded that the “timey wimey” nature of Doctor Who means that cause and effect are often inverted. When 13 helps 15 with something he can’t quite figure out, he exclaims, “I’m older than you!” The wisdom doesn’t travel linearly, because Who loves information paradoxes, but does the 13th Doctor remember this moment?
In some previous multi-Doctor episodes, like “Time Crash” or “The Day of the Doctor,” it’s made clear the past selves of the Doctor won’t remember crossing over with their future incarnations. But, with this moment, we don’t even know at what point from the 13th Doctor’s era we’re looking at. Right near the start? Before the return of the Master? After the revelations in “The Timeless Children?”
In a sense, none of that actually matters, because whenever this happened from the 13th Doctor’s perspective, it could very well be during a period of her life we didn’t see. The nature of Doctor Who is that of a time travel show, so we’re only seeing part of each Doctor’s story. This has been true since the start, but because this episode ends with a big regeneration, it’s particularly poignant. This may be the end of the 15th Doctor’s journey, but clearly, whatever aspects of his adventures we’ve seen are just a fraction of what actually happened.