(no subject)

[grassangel]

Asked by zabbers:I think it's actually canon-compliant! But: your puddle AU?

For those who don’t know, this is an AU/interpretation of canon that imagines that puddle of ‘oil’ from an alien ship is actually what happens when you leave a Time War TARDIS unattended for 70 years, which is what I headcanoned when I answered a question about where Missy keeps her TARDIS on a Master meme on twitter

So, and this is all preamble: Humanoid TARDISes are a thing.
Idris had The TARDIS consciousness placed inside her and there’s the whole holographic interface. Plus, when I saw this ask made to @evilqueenofgallifrey (which definitely influenced this headcanon/AU), I sort of went down the lore rabbit hole and found out that the TARDIS can appear in/have a humanoid form and that a companion had been changed into one. (There’s apparently more lore that the Master’s former TARDIS, a twin to the Doctor’s, was very fond of appearing humanoid and basically staged a coup on Gallifrey? but I didn’t find that out until after this headcanon had started to seed in my head)

These humanoid type TARDISes were involved in The War/War in Heaven, not The Time War, but if the Daleks can have puppets with eyestalks in their foreheads, the Time Lords can have their genetically modified, bred and enslaved humanoid TARDISes. Obviously being used in a war doesn’t necessarily make them a War TARDIS but-
In the Doctor Falls, Simm!Master confirms he took a TARDIS, one heavily implied to be a War TARDIS. Not all TARDISes used in the war are these humanoid TARDISes but TARDISes are sentient enough to communicate with one another, perhaps enough to give each other ideas…

So Missy has a War TARDIS. It’s probably well kitted out, plenty of defences, definitely has a working chameleon circuit, and certainly isn’t a type 40. We never see her TARDIS though, as apparently she parks well away from whatever scheme she has going on and instead uses a Vortex manipulator to travel short distances.

We don’t know where it was parked when she was arrested. But the Doctor can be sensible at times, so I’m willing to bet that she told him where it was and he towed it or she gave him her Stattenheim remote control to recall it, so that it wouldn’t be nicked like the Thirteenth Doctor was so concerned her TARDIS might be.

So it sits somewhere in Bristol for 70 years, disguised, because the chameleon circuit works. (That or Missy parked it there to begin with, as she does love keeping track of what the Doctor is up to.)
The chameleon circuit means it’s perfectly hidden and gently persuades people to move on and ignore it. So if it was parked in an empty lot just after WWII… that lot might just stay empty.

But 70 years in the same place could make a TARDIS antsy. It knows the Doctor’s TARDIS stole someone. It wants to fly again, so it starts looking for a pilot. It’s a War TARDIS, so it has a bit more initiative and can bond with a new pilot more easily than a model that isn’t expected to regularly have its pilots dying or fade in and out of existence.

It finds Heather. Or Heather finds it.
Either way, they both want the same thing. So it changes her. Okay, it got things a bit wrong and enmeshed itself a bit too closely into her biology, but it’s not used to working with humans.

So Missy’s TARDIS is now Heather. Or Heather is now Missy’s TARDIS. Or perhaps they’re both a little bit of each other.
They can still see the universe together though, so they do. (At least after clearing up the thing with Bill they do.) And doesn’t the whole seeing the universe together echo the promise the Doctor and the Master made so long ago?
Heather of course returns for Bill. And the TARDIS is happy to adopt (and manipulate the biology of) another pilot.

Being a TARDIS herself, of course Heather can pilot the Doctor’s. Probably even lets her know how she can be contacted just in case she and the Doctor needs some help. (And even outside of this AU, Heather and Bill occasionally hijack the TARDIS, much like River does, and take her for a spin because the TARDIS likes Heather, Heather likes Bill and Bill likes the TARDIS. It’s a bit of a weird threesome and Bill never wants to discuss it with either the Doctor or the kind of hot cougar lady they sometimes bump into. Especially cougar lady, as the TARDIS gives off a little chime in her presence that feels like she’s saying ‘daughter’ and just. No.)

But because she’s also Missy’s TARDIS, she went to collect Missy too. Her TARDIS couldn’t forget its mistress.
Though like… she just puts Missy in a safe place before continuing on with Bill, leaving Missy to kind of… hitchhike her way across the universe for a bit.

(Not necessarily a hard and fast part of this headcanon/AU, but Missy does track down Bill and Heather during their travels at some point and apologises for the whole cyber-conversion disaster and offers a ‘completely safe and non-deadly’ adventure as to make up for it. It’s meant to be just one. It turns into seven and at least three of those are decidedly not safe or non-deadly.)

Depending on how much I’m taking the novelisation of TUaT as canon in a given moment, Heather either joins up with Missy again after Bill dies or they both kind of… tag along as combo TARDIS/companions after bumping into Missy again. (There is more hand holding than Bill is entirely comfortable with.)

I think that was five? Probably more, given I feel like this is basically not!fic/something that would otherwise be called an outline, but the following are the hard and fast things

1. Missy’s TARDIS was in Bristol.
   
2. The TARDIS chameleon circuit meant it was invisible and deterred people from where it was parked.
   
3. It was the puddle in that empty lot
4. It adopted/changed Heather to become its new pilot, both of them combining/merging to become something similar to Compassion, the first and only, humanoid type 102 TARDIS
5. Being a TARDIS herself now, of course Heather knew how to pilot the Doctor’s TARDIS
6. Missy’s TARDIS is at least a little faithful to her mistress and does save her from the colony ship
7. Missy’s TARDIS/Heather does return to Missy at some point

(Definitely not a part of this headcanon/AU, but the Doctor’s TARDIS definitely got Ideas after the run-in with Pilot!Heather and convinced Missy to give her a few upgrades that would give her some of the features of the humanoid type TARDISes.)