Fans were shocked in the run up to this yearsDoctor Who revival that former showrunner Steven Moffat would return to the TARDIS and write his first episode for the series since he departed in 2017, only to be shockedagain when it was quickly confirmed that he would also write the 2024 Christmas special for the series. But it turns out that at least part of the reason why we got that double-barreled release of news is for a simple reason: Russell T Davies is really,really busy. Davies had planned to pen the second Christmas special of his sophomore tenureand had previously teased progress on it while discussing Whos return to the traditional festive TV slotbut, according to Moffat, constraints on the showrunners time as Doctor Who ahead of Ncuti Gatwas second season as the Doctor necessitated a change in holiday plans. The email [from Davies] came through and said Steven, Ineed to get on series 2, Im never gonna this Christmas script could you come in and write one?' Moffat recalled in a new interview with BBC News. Not complete his script, but do another one from scratch. Production on the second season of Davies new era began very quickly after conclusion on the first. Fans saw set pictures of the incoming companion played by Andors Varada Sethu well before she was formally introducedand even before Gatwas first season began airing. Its no surprise then, that Davieswho already, for better and worse, scripted the majority of Gatwas first season himselffound himself in need of another writer when turnaround was so demanding.As for why Moffat returned, the writer added both a professed love for writingDoctor Whos seasonal episodes, but also teased the central hook to the upcoming episode, titled Joy to the World. Imagine in the far far future a hotel chain got hold of the idea of time travel, Moffat teased. Whats the first thing a hotel chain would do if they had time travel? Theyd realize they had an opportunity to sell all the unsold nights in their hotels in history.Its presumable one of those unsold nights, then, that brings Gatwas 15th Doctor crashing into the life of Nicola Coughlans new character, Joy, as well as the return ofDoctor Whos ancient amphibian foes, the Silurians. A Time Lord is a bit more than any hotel could bargain for if it came to time-travel reservations, it seems. Joy to the World is currently expected to broadcast on the BBC in the UK, and Disney+ internationally, on Christmas Day. Want more io9 news? Check out when to expect the latest Marvel, Star Wars, and Star Trek releases, whats next for the DC Universe on film and TV, and everything you need to know about the future of Doctor Who.