Doctor Who reveals the Doctor's feelings for Yaz in Legend of the Sea Devils

This followed much discussion among fans as to the possible romantic nature of the pair's relationship, with many rooting for the potential couple they'd nicknamed "Thasmin" – that's "Thirteen and Yasmin" for the uninitiated.

Yaz actress Gill recently told RadioTimes.com that the duo's dynamic would be at "the heart" of next episode Legend of the Sea Devils and sure enough the special did dig deeper than ever before, with the Doctor directly addressing Yaz's feelings – and her own – for the first time.

In an effort to uncover the wreck of a pirate ship once captained by Ji-Hun (Arthur Lee), the Doctor took Yaz on a breathtaking trip to the bottom of the ocean, quipping, "Not a bad date, am I?" – it was a thoughtless comment which clearly upset Yaz and the Doctor instantly knew it, what with Dan having confronted her about Yaz's feelings in Eve of the Daleks.

Dan seemed convinced that the Doctor reciprocates these feelings ("Come on, Yaz," he says to his friend. "Can't you see it?") but we were made to wait a little longer before the Doctor herself finally addressed the elephant in the room.

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As the episode reached its dramatic climax and the Doctor worked to thwart the Sea Devil plot to flip the Earth's geomagnetic poles and flood the planet, she decided that the time had finally come to discuss her dating life...

"If I was going to [be in a relationship], believe me, it’d be with you." she told Yaz. "I think you’re one of the greatest people that I’ve ever known, including my wife [Alex Kingston's River Song].

"If it was going to be anyone, it’d be you. But I can’t."

When Yaz questioned why they couldn't be together, the Doctor's response was simple and brutal: "There’s no point. Time always runs out."

Long-time fans will recall the Tenth Doctor (David Tennant) having a similar conversation with Rose Tyler (Billie Piper) when finally confronted as to the nature of their relationship. "I don't age," he said in the 2006 episode School Reunion. "I regenerate. But humans decay. You wither and you die.

"You can spend the rest of your life with me. But I can't spend the rest of mine with you. I have to live on, alone. That's the curse of the Time Lords."

The Thirteenth Doctor tells Yaz something similar in Legend of the Sea Devils' final scene as the pair share a heart-to-heart before leaving 19th century China. "Yaz, I can’t fix myself… to anything, anywhere, or anyone. I’ve never been able to. It’s what my life is.

"Not because I don’t want to. Because I might. But if I do fix myself to somebody, I know sooner or later, it’ll hurt."

"Can we just live in the present, of what we have, while we still have it?" she asks – and Yaz reluctantly agrees.

For "Thasmin" fans, Legends of the Sea Devils might feel like a mixed bag – though the Doctor finally acknowledged Yaz's feelings and even admitted to harbouring her own, she also seemed to put the kibosh on any sort of long-term romantic relationship.

Doctor Who producer Matt Strevens had previously indicated that this storyline might end in heartbreak. "I think that’s a constant thing the Doctor’s grappling with – how close to get to her friends and companions," he said back in February. "Obviously it’s a special bond [that the Doctor has] with Yaz, because they’ve spent so much time together. Who knows how it will end between the two of them?"

Mandip Gill – who is set to depart the show alongside Jodie Whittaker in the next episode – has also promised "a lot of tears" when her exit storyline plays out. "But I loved where it ended up," she added. "I think it was the right thing. It's exciting. There's a lot of emotion."

Doctor Who will return to BBC One and BBC iPlayer later this year for a special episode to mark the BBC's centenary.

Read more about Doctor Who:

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• Doctor Who: Legend of the Sea Devils podcast review
• Who was Madame Ching? The real history behind Doctor Who: Legend of the Sea Devils
• Doctor Who's Legend of the Sea Devils ends with regeneration hint
• Doctor Who finally addressed the River Song elephant in the TARDIS

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