A short story, part fixfic, part character study, set between Oxygen and Extremis, and containing major spoilers for both episodes. You have been warned.
I wrote this following an online discussion, about some of the plotholes in Extremis. This is not a very good fanfic, mostly because I don't really enjoy writing and just rush through it as quickly as possible. Sorry. Unfortunately, the story just had to be written and wouldn't go away. So here it is.
TRUTH AND CONSQUENCES
Missy's fingers pause, mid bar, before slamming down on the piano keyboard in a loud discord. Her hearts just aren't feeling the music today.
"It's all his fault," she mutters to herself. She's muttered something similar countless times every day for years, but this time she's surprised to find she means it.
Until yesterday, the Doctor had been doing his best to make her long captivity bearable. Her favourite food, books, films, the piano, and - best of all - his company. Just simple conversations between friends, almost as if they weren't gaoler and captive.
Until yesterday.
There had been something different about his voice. That was the first thing she noticed. It was weaker, wallowing in misery and self-pity. Not like him at all. Only then did his words sink in:
"I'm blind, Missy. I'm blind."
He had stayed there, outside the vault, for hours. Not coming in. Not wanting her to see him like this. Just whinging about his misfortune, expecting comfort and sympathy from her. Why? He must've known he'd picked the wrong person for that. Comfort and sympathy had never been her strong points.
Missy mutters to herself again: "What did the fool expect to do? Give up one of my own eyes for him?"
She sighs and shakes her head, dreading his next visit and a repetition of that smothering sentiment.
BEEP
The sudden noise cuts through her thoughts. It's coming from her chest, from the brooch pinned to her jacket. Quickly, she hits a random bunch of piano keys, drowning the sound. He can't know about this. It's her one little victory over him, and - despite everything, despite their friendship - she doesn't want to lose it.
After only a second or two, the sound fades. She removes the brooch, and stares into it. Tiny illuminated display circuits flicker into life in response. The message is clear. Apparently, someone has scanned the vault with a sentient sensor beam. Scanned the vault and how much more?
She gets up from the piano stool and looks over to the far corner of the room. There, on a small table, beside the remains of her lunch, is an old Commodore 64 computer plugged into a portable black-and-white telly.
"I can't allow you anything more powerful," the Doctor had said when he gave it to her. "But look on the bright side. At least it's not a Jupiter Ace."
Now putting the brooch down on the table, she says, "Oh, Doctor, If only you'd known about this!"
She turns back to the piano, opens it up, and pulls out the thinnest of the metal strings. Then back to the table again. She grabs the steak knife and begins cutting the wire into smaller lengths. It's hard work, and slow. When she finishes, the knife is well and truly blunt.
"Hate to think what baldy will make of that when he takes it away." She grins, her previous worries forgotten.
Now comes the tricky part. Removing the back from brooch, she exposes the nanocircutry inside, then she uses the wires to connect it up to the computer's serial port, and manages to seal them in place with bits of grease from the plate.
"Not the first time I've used food to make a computer system." She smiles again, the grin growing to Cheshire Cat proportions when she remembers what he said about that - even though, strictly speaking, the memory isn't exactly hers.
She switches on, waits for the TV to warm up, then starts to type, using the Commodore to interface with her brooch computer. What she sees shocks her. The beam wasn't just scanning the vault, but the whole Earth. And the Quantum Fold around her vault means this was probably the one place on Earth that the unknown snoopers hadn't managed to get a clear scan of.
"Well, aren't I the lucky one..."
She pauses. This can't be a coincidence. As soon as the Doctor gets himself blinded, this happens. Someone is obviously planning to take advantage and invade.
"Oh no you don't! Taking over the Earth is my job. And my hobby too. I'm not going to sit here all meek and quiet and let you take that away from me." She briefly adopts an exaggerated prim and meek pose to illustrate her point, before relaxing into nervous energy again.
It's fairly easy for her to trace the beam back to its source. Not a race she knows, but then one being is pretty much like another as far as she's concerned. There's her, then the Doctor, then everyone else, and that's it.
Luckily the aliens' system isn't as advanced as she feared, and she manages to establish a link to it. What she finds there almost leaves her lost for words.
A simulation of the entire Earth. Everything. Everyone. All duplicated down to the last detail. Well, almost. The Quantum Fold has done its job. She is the one thing they don't know about. The trickster in their pack. The one person who could disrupt their dress rehearsal.
But what to do? Should she just delete the whole thing? No. That will just make them suspicious. Besides, they probably keep backups anyway. It has to be something subtler. Something they wouldn't notice. But what? There's no point deleting the Doctor or those interfering UNIT busybodies from the simulation. Again, it would be noticed.
A few more tests reveal that the system's weakest point is the random number generator. It could easily be hacked to just use one seed for all its calls. But that won't help much on its own. There must be something else she can do.
"Think Missy! Think!" She yells at herself in frustration, then angrily picks up a book and throws it across the room.
"A book..." Why does that thought seem important somehow? "Yes! That's it!" She leaps up from her chair, and starts dancing a little jig.
"Who's the Mistress with the plan, who's great for you and me?" she sings. "M-A-S, T-E-R! M-I-S-S-Y!"
Finally, she sits back down, and begins typing. Her fingers move across this keyboard far more swiftly and confidently than they did across the piano's.
The aliens might not notice if something is added to the simulation. Something small, and insignificant, but with the power to be the greatest weapon in their make-believe world. Something like a book.
Purring to herself, she types the word, "Veritas".