Who is Brendan in Doctor Who - and are we in for another Time Lord twist?

Later, Brendan (played by Evan McCabe) decides to join the Guards (Irish police) himself, citing his desire to “make a difference”, though his career is apparently cut short when he’s shot by a thief and falls off a cliff onto the stony beach below. Shockingly, though, Brendan wakes up unharmed – and that’s when things get even stranger.

Towards the end of the episode we catch up with Brendan as a respected elder officer, given a carriage clock as a retirement gift and leaving the Gardaí station for the last time – only for him to be greeted by his father and the sergeant from earlier, who haven’t aged a day since he was a young man and request that he return to the “back office”.

“We have to get rid of everything I’m afraid,” Brendan’s father says as they strap him into a machine and handcuff him to a chair.

“Thank you for your service,” adds the Sergeant. “We’re sorry you won’t remember it.”

At this stage we leave a screaming Brendan behind and the episode returns to the Doctor and company dealing with the Cybermen, with viewers none the wiser about who Brendan is, what’s happening to him or what significance he has to the plot.

Presumably, we’ll get some answers in the series finale The Timeless Children – but with so much already set up to be resolved in episode 10, it seems fair to assume that the Brendan scenes must tie into some already-established mystery in the series, namely:

• What are the Cybermen planning?
• Who is the Timeless Child?
• How does the new Fugitive Doctor fit in the Doctor’s life?

And with that in mind, we have a few theories about how Brendan factors in to the series’ final episode…

It’s a Cyberman simulation

Given that this episode was named for the Cybermen, at first it seemed fair to assume Brendan’s story had something to do with the silvery cyborgs. Was he a future recruit? Or was this odd, dream-like existence some sort of simulation put in place, convincing converted humans that they were living a nice life while actually trapped within the metal body of a Cyberman (basically, a bit like the Matrix)?

Given the strange events of Brendan’s life, the latter could be possible – but why wouldn’t this twist just be revealed in the initial episode? Why would we be following the inner life of some random Cyberman? And if this was something that happened to all Cybermen, why haven’t we heard about it before?

Maybe this somehow relates to the Cyberium AI, or Ashad’s (Patrick O’Kane) mysterious plans for the “Ascension” of the Cybermen that somehow involves Gallifrey.

Or perhaps a larger mystery holds the answer…

Brendan is a Timeless Child

We’re expecting answers about the Timeless Child in the finale (it is called the Timeless Children, after all) – so could Brendan’s story somehow relate to that, and the supposed “lie” that the Doctor’s home planet Gallifrey was founded on?

Just think about it. Brendan is found as a baby, and his life has a “timeless quality” – he apparently can’t die, and key figures in his life apparently don’t age.

Maybe there are multiple children in odd simulations like Brendan’s, living a life before having their memories wiped and started again, and somehow this scheme was set up by the Time Lords to in some way service Gallifrey.

Yes, it’s a bit vague, and it doesn't tie into the visions the Doctor had about the Timeless Child before (see above) – but without knowing who or what the Timeless Child is, it’s hard to know how it ties together.

Unless of course, the answer is staring us in the face.

Brendan is a Time Lord

In this series’ fifth episode Fugitive of the Judoon, fans were gobsmacked when tour guide Ruth Clayton (Jo Martin) was unveiled as a previously-unknown incarnation of the Doctor, hiding in Gloucester having turned herself human using a chameleon arch (a device previously used by David Tennant’s Doctor and Derek Jacobi’s Master).

So could Brendan be in a similar situation? Notably, the camera appears to focus in on the carriage clock he received upon retiring from the Guards, which ticks along while he’s manhandled by his dad and former boss. Similar ticking clock imagery appeared at the beginning of Fugitive of the Judoon as a hint of Ruth’s Time Lord origins, so it could be that this is an intentional mirroring.

And while Ruth hid her Time Lord energy within a fire alarm, we’ve previously seen both the Doctor and the Master place it within fob watches – so could a carriage clock perform the same function?

It certainly seems possible. We’ve heard an example of a chameleon arch changing a grown Time Lord into a child before (Derek Jacobi’s Master used one in that fashion, as recounted in 2007’s Utopia), and the pain Brendan experiences while wired into the machine isn’t dissimilar from when we saw the Tenth Doctor change himself in 2007’s Human Nature.

Even the two mysterious figures apparently guarding Brendan aren’t without precedent. Ruth had her “husband” Lee (Neil Stukes) guarding her while in possession of his Time Lord memories. And maybe Brendan’s miraculous survival after falling from the cliff and/or being shot is another protective feature of the device, shielding the Time Lord user from harm while they’re more vulnerable.

At a pinch, yes, it mostly fits – even the painful memory wiping at the end, which could be the two men “resetting” him with the chameleon arch once again now that he’s basically seen this human life out.

But if this is a Time Lord, who could it be? Another version of the Doctor, pre-or-post-Ruth, being held captive by the Time Lords? An incarnation of the Master before he became the current Sacha Dhawan version (in which case, the idea of this imprisonment may have been rehabilitative)? Or someone else entirely, who may (see above) relate to the Timeless Child mystery?

Look, if this turns out to be the first male version of the Rani you heard it here first.

Or – something new for the next series

We left one option off the list higher up, because it’s not a mystery exactly – but could it be possible that Brendan doesn’t relate to this series at all?

After all, series boss Chris Chibnall recently said that the series finale would seed new plot developments for the already-confirmed series 13. What if this strange, apparently unconnected storyline is setting up something for then?

Perhaps Brendan is some villain in an alien prison, or the simulation is something the Doctor will come across herself, and we’ll only get partial answers to the whole thing in next week's The Timeless Children. Also, when he returns to life it looks similar to the effect on John Barrowman's immortal Captain Jack Harkness - could the recently-returned Jack be related to Brendan in some way?

The only downside to this theory is that it seems a little unlikely that Chibnall would devote so much time in the finale to something we won’t see in action for over a year, especially when he has so much to resolve here anyway.

In short, then, the relevance of Doctor Who’s Irish subplot is still a mystery to us all. Here’s hoping it’s worth all this speculation when we find out the real answers in episode 10.

Doctor Who series 12 concludes on BBC One at 6:50pm on Sunday 1st March