A Classic Doctor Who Reference Just Opened Up A World Of Possibilities

This post contains spoilers for the latest episodes of "Doctor Who."

There's a moment in the latest episode of "Doctor Who," a campy, big-hearted, Beatles-featuring riff on the importance of music, in which the Doctor opens up a bit more than fans might expect. It's been clear since last year's introductory episode that Ncuti Gatwa's era of the long-running sci-fi series (which is also former showrunner Russell T. Davies' second era) will be different from the "Doctor Who" we've seen before. As the Fifteenth Doctor, Gatwa infuses the show with a sense of modernity. He's openly queer, Black, and a Millennial, and he performs the lead role with a precise and deeply endearing sense of emotional openness. Die-hard fans of the series can quickly count the amount of times the Doctor has cried in the past, but Gatwa's Fifteen has already had tears welling behind his eyes a few times in his three episodes and counting.

All of this is to say that when the Doctor starts talking about his own backstory — his adoption, his status as a genocide survivor, and the family he might still have left — it's not as surprising as it would've been if, say, Peter Capaldi did it. It makes sense that The Doctor's first ever bi-generation (a twist that allowed a brief David Tennant return) would stir up more feelings than usual about the way the Time Lord moves through the world, as would his newfound friendship with Ruby Sunday (Millie Gibson), who has her own complex and mysterious adoption story to reckon with. The moments of sweet, heartfelt exposition between the two are lovely, but the real surprise comes when Fifteen mentions a long-lost character offhand: Susan Foreman.

If you're a fan of new "Who" and Susan's name doesn't ring a bell, that's because she appeared in the earliest episodes of the original series, acting as one of the companions to the First Doctor (William Hartnell) from 1963 to 1964. Susan (Carole Ann Ford) was the Doctor's granddaughter and seemed to have lived with him on Gallifrey before coming to earth. The pair live in London in the show's first season, but when two of Susan's teachers become suspicious of her otherworldly knowledge, they end up in the TARDIS alongside her, and the Doctor takes all three of them on galaxy-spanning adventures.

Ford wanted to leave the show by its second season because, as she told the Daily Mail, "My character was going nowhere. In truth, I wished I had never gone into it." By that point, the first season had already aired an incredible 42 episodes, surely a demanding production schedule for any actor. Writers crafted a storyline in which Susan fell in love with a freedom fighter named David in a future, Dalek-occupied version of London. The Doctor left her to build a life with the man she loved, but said he'd return to her one day. The only time Susan has appeared on screen in the main show since was in the 1983 special "The Five Doctors," when she's pulled by a Time Scoop that reunites her with her grandpa, as well as future iterations of the Doctor.

In-show references to Susan have appeared sparingly, and they haven't always been optimistic. From the show's 2005 revival onward, The Doctor has been mostly characterized as the last of his kind, and has at times stated outright that his whole family is dead. Both the Tenth and Eleventh Doctors mention that they haven't looked for Susan to personally confirm her death, and an episode from Twelve's run, "Death in Heaven," sees companion Clara (Jenna Coleman) confirm that Susan is missing and presumed dead. In the latest episode, Fifteen says something similar, but it's clear that Ruby's adoption story has him more curious about his own family than ever. "I live over there," Fifteen tells Ruby when pointing towards the area where Susan and the First Doctor lived in 1963. "Shoreditch! I'm there right now!"

The Doctor seems genuinely delighted for the trip down memory lane. "1963, I park the TARDIS in a junkyard and I live there with my granddaughter Susan," he explains with a laugh. When Ruby is clearly curious, he teases, "We could go and have a look, but you know, timelines!" The Doctor makes a whoosh noise indicating the complexity and potential explosiveness of messing with his own timeline. When Ruby gets giddy about the idea of finding Susan in the present day, the Doctor grows more solemn. "The Time Lords were murdered," he explains. "Genocide rolled across time and space like a great big cellular explosion, maybe it killed her too."

Ruby and Fifteen laugh the conversation away with a comforting hug that feels totally in line with the energetic, close relationship they've already formed. But is this the last we'll hear about Susan until the next actor takes over the show's lead role and explains themself all over again? Hopefully not. Susan has lived several full and sometimes tragic lives in "Doctor Who" audio dramas and novels, but she has never gotten the closure she deserves in the context of the flagship series. 

Ford is now 83 years old, but she's reprised the character in podcasts as recently as last year. In 2023, she told Radio Times she was itching to return to the series, and even pitched ideas for her character's reintroduction. "I'd love to be in it as it is now!" she told the outlet, adding, "I'd love to experience all the money they spend on it now — it's done like a film!" In a timey-wimey show where anything is possible, it feels like it's past time to reunite the Doctor with the long lost family member who was quite literally by his side since day one. The Doctor's newfound sense of emotional openness is the perfect lens through which to re-explore his own original backstory, which has too often gotten lost among so many other adventures. Bring back Susan Foreman!

New episodes of "Doctor Who" premiere Fridays at 7pm E.T. on Disney+, and at midnight G.M.T. on BBC iPlayer in the UK.