Doctor Who returns to television screens this November for the sci-fi series' 60th anniversary. Three specials are due to mark the occasion and they will be the first episodes of returning showrunner Russel T Davies' new era. Davies isn't coming back to Doctor Who alone, though. Before Ncuti Gatwa, takes over as the Doctor, fan-favorite actor David Tennant is returning for the specials, this time as the Fourteenth Doctor. Tennant will also be reunited with his old companion, Catherine Tate's Donna Noble, who originally had her memories of the Doctor erased.

Tennant's return as a new incarnation of the Time Lord raises a host of questions, but Donna's return might just raise even more. When she was last seen in Doctor Who, not only was Donna completely oblivious to the fact she had ever traveled with the Doctor, but the Time Lord had warned Donna would die if she ever remembered him. The mind wipe was made necessary when Donna became part Time Lord, but was unable to withstand a Time Lord consciousness. While "The End of Time" highlighted the danger Donna faced if she ever remembered the Doctor, the series never got to explore how becoming a human-Time Lord hybrid might have affected Donna.

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Donna's Time Lord Biology Could Factor Into Doctor Who's 60th Anniversary Specials

Donna Noble as the Doctor-Donna in Doctor Who

The BBC recently released a cryptic trailer for the upcoming Doctor Who specials. While the teaser is only short and gives very little away, one of the few recognizable shots that appears is of Donna reaching out to the Doctor's spare hand in Season 4's "Journey's End." The episode saw the Tenth Doctor avert an early regeneration by projecting the regeneration energy into his spare hand (the one he lost and regrew in a sword fight with the Sycorax). Donna later made contact with the hand and the combination of regeneration energy, the Doctor's DNA and Donna's DNA led to the creation of a part-human copy of the Doctor. It also led to Donna's transformation into a human-Time Lord Meta-Crisis.

The fact this shot from "Journey's End" has been included in a Doctor Who teaser is telling. Rather than using a shot from the later scene in which the Doctor actually wipes Donna's mind may suggest the specials are not only addressing Donna's lost memories but the biological change that took place. "Journey's End" did little to address the exact nature of Donna's transformation, only stating she had gained the Doctor's Time Lord consciousness. However, the fact she was referred to as "part Time Lord" implies there was a physical change, beyond Donna simply absorbing the Doctor's knowledge. If this is the case, Donna has been living her life totally unaware that she's not completely human.

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Catherine Tate as Donna-Noble looks surprised in the Doctor Who 60th Anniversary Special

Some Doctor Who fans have already taken it upon themselves to attempt to decipher the cryptic teaser's true meaning, with reversed versions appearing online. Once played backwards, Donna's voice can be heard in the teaser. She asks: "Why did this face come back?" The fact Donna is the one asking this question, rather than the Doctor himself, is particularly interesting. Perhaps her mind is not quite as disconnected from the Doctor's as he had hoped. Maybe the Doctor's regeneration into his past incarnation has triggered a connection between them. It was specifically the Tenth Doctor's DNA and consciousness that Donna absorbed, after all.

Clearly, something has brought the Doctor and Donna back together. The Time Lord would not voluntarily return to the one companion he is endangering with his very presence. It seems likely that whatever has reunited them is tied to Donna being rendered part Time Lord by the Doctor's regeneration energy. A previous full-length trailer for the upcoming specials saw the Doctor claiming "if destiny exists, then it is heading for Donna Noble," suggesting greater forces are at work around Donna and himself. Maybe Doctor Who's 60th anniversary is about to pay off a storyline that began in Donna Noble's last adventure.