This article contains spoilers for The Time Traveler's Wife episode 1.

Some viewers may believe The Time Traveler's Wife steals plots from Doctor Who - but in reality, it's the other way round. Time travel is a theoretical science, and in truth, the concept is usually used as a plot device. In The Time Traveler's Wife, the model of time travel allows a strange, out-of-sequence romance to develop between Henry DuTample and his future wife Clare Abshire.

The plot may be familiar to viewers who are familiar with Doctor Who, the longest-running science-fiction TV series in the world. The out-of-sequence romance is reminiscent of "The Girl in the Fireplace," a story broadcast in 2006 in which Tenth Doctor David Tennant interacted with Madame de Pompadour throughout her life. Two years later, Doctor Who revisited the idea when it introduced the character of River Song, a woman who was gradually revealed to be the Doctor's future wife. River Song's story was told over the next few years, as she interacted with Eleventh Doctor Matt Smith and Twelfth Doctor Peter Capaldi. She even carried a journal in which she recorded her adventures, allowing her to check with the Doctor and figure out how their timelines were intersecting. Doctor Who's River Song is clearly similar to Clare in The Time Traveler's Wife, right down to the notebook.

Related: The Time Traveler's Wife Cast, Character, & Changes Guide

The Time Traveler's Wife TV series may be releasing in 2021, but in fact, it's based on the debut novel by Audrey Niffenegger. This had a profound influence on Doctor Who writer and showrunner Steven Moffat, which would eventually lead him to pen "The Girl in the Fireplace" as something of a homage to the sci-fi book. "It’s very similar in mood if not in detail," he admitted in a recent interview with the Radio Times. "It’s about a time-lapse relationship, and I did it quite consciously - knowing I was doing The Time Traveler’s Wife." Niffenegger noticed the similarity, and made a nod to it herself in a later novel where a character was watching that particular episode. Moffat then created River Song, the Doctor's wife, making the reference more obvious.

River Song is in a space suit in Foctor Who.

In thematic terms, then, it isn't that The Time Traveler's Wife is inspired by Doctor Who; rather, it's the other way round. But viewers can be forgiven for noticing a stylistic similarity between the two shows as well, simply because Steven Moffat - former Doctor Who writer and showrunner - is in fact the writer and producer of HBO's The Time Traveler's Wife. Having loved Niffenegger's novel since it was published in 2003, Moffat is getting the chance to adapt it into a TV series.

This likely means audiences who are familiar with Doctor Who will find themselves responding to the HBO show in a similar way. Hopefully The Time Traveler's Wife will avoid Moffat's greatest problem, though - his tendency to get so caught up in the "timey-wimey" ideas that the plot becomes impenetrable. So far, the adaptation looks to be a faithful one, meaning The Time Traveler's Wife has a chance of recreating the emotional intensity of the novel.

More: HBO's Time Traveler's Wife Admits The Worst Thing About The Book & Movie