The Time Traveler's Wife writer Steven Moffat reveals an early Doctor Who episode of his was actually based on the original novel by Audrey Niffenegger. The Time Traveler's Wife is a new HBO Original series written by Moffat, which tells the story of Clare (Rose Leslie) and Henry (Theo James), two lovers whose relationship is complicated by Henry's uncontrollable ability to travel through time. The series is set to begin streaming on HBO Max on May 22.

As The Time Traveler's Wife is based on a novel, and there has already been one film adaptation starring Rachel McAdams back in 2009, the property comes with a fanbase who have some pretty high expectations of Moffat. Of course, he is no stranger to dealing with passionate fanbases. Aside from being the mind behind the BBC shows Sherlock and Dracula, Moffat first made a name for himself as a writer on the hit British sci-fi series Doctor Who. Moffat first began writing for the Doctor Who reboot series during season 2, and then took over as its showrunner when it hit season 5.

Related: The Time Traveler’s Wife Must Avoid Steven Moffat's Story Problem

Now, in an interview with Radio Timeshe reveals he was inspired by Niffenegger's novel when he wrote the Doctor Who episode "The Girl in the Fireplace." While the episode certainly uses the time travel elements present in the book, Moffat describes the episode as "very similar in mood if not in detail." However, when Niffenegger released her second novel, she included a character who watches Moffat's Doctor Who episode, to inspiring the writer to lean further into its themes and create the Doctor's wife, River Song. See his full quote below:

It’s very similar in mood if not in detail. It’s about a time-lapse relationship, and I did it quite consciously - knowing I was doing The Time Traveler’s Wife. In my time on Doctor Who, I was more interested in the time travel aspect than most people probably are - I loved time conundrums and paradoxes. [...] She has a character in the book actually watching The Girl in the Fireplace on television, so I knew she was onto me. At which point I could be more obvious, so I made Doctor Who a wife - River Song.

The DOctor with the Girl in the fireplace in France in Doctor Who

Of course, once Moffat has pointed out the similarities, it is easy to see how The Time Traveler's Wife inspired his Doctor Who writings, especially the episodes which came out of the seasons for which he was showrunner. The character of River Song (played by Alex Kingston) serves as the titular Doctor's wife, and must live with the fact that she will always be meeting the Doctor out of order, due to his constant time travelling. This, of course, is almost identical to what Clare must come to terms with about her relationship with Henry in Niffenegger's novel.

While Moffat has never revealed exactly what the author's reaction to River Song's storyline on Doctor Who was, it can't have been too harsh, as she gave Moffat permission to adapt her book for the screen. At the very least, Moffat has proved he has a passion for the material, and the writing skills to be able to handle a complicated plotlineWhile Moffat certainly has some high expectations placed on his adaptation of The Time Traveler's Wife, after all these years of being inspired by the material, perhaps no one's expectations are higher than his own.

More: Doctor Who: River Song's Story In Chronological Order Explained

Source: Radio Times