Yaz picks up her pace when the security doors begin lensing shut one after another like alien eyes.
"Doctor?" she calls over her shoulder. "I think we'd better hurry up."
"Hm?" The Doctor looks up from the round, reflective tablet she'd hacked and registers the closing doors. "Ah! So that's what those symbols mean! Lovely. Good to know."
The sonic screwdriver's familiar buzz layers over the hum of the metal plates, a jarring note in their well-oiled synchrony. Yaz breathes a sigh of relief: the doors seem to have stopped moving.
"Which way next?" asks Yaz when the Doctor catches back up with her.
"Let's see... holding cells, holding cells..." She scans the tablet, turns it sixty degrees clockwise. "Next left, then down a level and two rights in a row."
They're nearly to the first cross-corridor when the Doctor hmms in the way Yaz has come to recognize and whips out the sonic again.
"What is it?" Yaz asks when no explanation is forthcoming.
The Doctor gives the sonic a vigorous shake, then scowls at it. "Incompatible software, it looks like. Some of the marginal subionic cross-frequencies are generating enough interference to activate the security backups."
Yaz takes a moment to parse through this. "What backups, exactly?"
As if in response, the security doors resume closing again, though more slowly than before, stuttering a little -- not so smooth this time. Without exchanging a word, Yaz and the Doctor both break into a run, taking the left turn at an ordinarily inadvisable speed, and --
Yaz's hand shoots out instinctively, steadying the Doctor. Fight, flight, or finesse?, she wonders, but when she looks up at the red-haired, human-looking man they'd collided with, she experiences a sort of full-body stutter. The sharp nose, the cheekbones for days, the wide-eyed startle in perfect mirror as he stares at the Doctor and she back at him...
"Uh..." Yaz says slowly. "You know this person, Doctor?"
"Well, not exactly -- " the stranger says, looking at Yaz, at the exact moment that the Doctor does the same and says, "In a manner of speaking, I -- "
They look back at each other again.
And that's when the tiles beneath them drop away.
Yaz reflects that the silence you get after a good rousing stretch of terrified screaming is really a cut above your garden-variety silence. She can practically hear it ringing in her ears -- or is that just aftershock from the screaming?
"On the bright side," the Doctor says into the ringing which is maybe silence and maybe mild eardrum trauma, "we are headed for the holding cells. I reckon this is probably what got Ryan and Graham!"
"You reckon?" With a groan, Yaz props herself up against one wall of the... prisoner transport, she supposes. There's barely a sense of motion now that they've stopped falling, and the tiny room's sides are all shadow-hoardingly opaque, but according to the hacked tablet -- which the Doctor somehow managed to keep in one piece, though maybe that's just alien tech for you -- they are in fact moving at a stately pace through the facility.
The dim glow from the tablet is the only light in the transport, and it paints the Doctor's face with faint, color-coded blurs of reflected techno-nonsense as she frowns over it. "What I don't understand," she says, "is why the active security protocols, well, activated. Incompatible cross-frequencies or no, the exploits I was using should have been well under the detection threshold for state-of-the-art 26th-century Dlivghu technology."
In the opposite corner of the transport, the stranger clears his throat. Yaz whips round to face him. "Ah... yes," he says. Yaz can't see his face in the darkness -- he's hardly more than a silhouette in the corner -- but she finds she can imagine the look of rampagingly breezy innocence in full detail. "Indeed. I believe I may hold the answer to that one."
There's a rustle of cloth, a click, and --
"That's not your sonic, is it," Yaz observes. The color's all wrong, the shape unfamiliar, but it's making that same resonant buzz.
"Well, actually -- " the stranger begins.
"I was talking to the Doctor."
"Well, actually -- "
"Oh you know what she means," the Doctor interjects. The stranger subsides. "Sorry," she adds, "but I think we ought to lay our cards on the table, hmm?" She nudges Yaz with a shoulder and nods at the stranger. "Yaz, love, that's me. Well, sort of me. Well, when I say 'me' -- "
"Clone?" Yaz supplies. "Evil twin? Fetch?"
The Doctor blinks.
"Okay, probably not that." Yaz knows she's babbling, a bit, but she wants quite badly to put things back in order and words are all she has right now.
"You could call us timeline twins, I guess," the Doctor allows.
"Yes, you seem to be some sort of... branched-off version of me," the stranger says.
At this the Doctor -- Yaz's Doctor -- leans back, insomuch as the cramped space allows. "Eh?"
"A branched-off version of me."
"Who's calling who a branch now?"
"Well," says Mister Tree, "considering the tachyonic signature of the quantum trail I was following, the divergence point was probably four or five convolutions down, which means I am -- "
"How about 'not helping'?" Yaz suggests.
Both Doctors turn a guilty glance toward her then -- his slightly astonished, hers embarrassed. Yaz can almost feel their feathers unruffling.
"Right, then," says Yaz's Doctor, tapping at the tablet once more. "It looks like we'll be at the cells soon. Let's see if we can't get our sonics working together, shall we?"
Afterward, when Ryan and Graham have been bundled off to the decontamination pods to neutralize the last of the paralytic gas that the spacefleet were using as prisoner control, Yaz carefully, and with great dignity, drapes herself against one of the great curving struts of the TARDIS. She has no idea just where the TARDIS was keeping decontamination pods -- just the three, she wonders, or is there some kind of pod-printer churning them out on demand -- but thinking about extradimensional spaces inside extradimensional spaces is, frankly, giving her a headache.
The Doctor regards her with an air of carefully restrained fussing-over, which Yaz appreciates -- the restraint, not the fuss. "I'm fine," she says in answer to the unasked question. "Really, I held my breath most of the time." If she's being honest with herself, the headache probably isn't just from the dimension paradoxes, but she has absolutely met her monthly quota of being stuck in cramped spaces. A few more hours of headache is a price she's willing to pay.
"That was pretty good breath-holding, for a human," the Doctor says encouragingly.
Yaz smiles lopsidely and closes her eyes. "Our mum said we both ought to learn an instrument. I wanted the bassoon originally because it sounded so impressive -- the name, I mean, 'bassoon' -- but she talked me down to flute or clarinet. I picked flute."
"Hah!" The Doctor's laugh is an explosion of sudden delight against the TARDIS's gentle thrum. "Saved by flute lessons. Saved by music. I love it."
"I suppose if I'd gotten my way I'd still have pretty good lung capacity," Yaz says. "For a human." She doesn't want to open her eyes -- the pulsing, warping TARDIS lights, with their everpresent hint of manifold space, are not the best accompaniment to unassisted detox from alien chemical weapons -- but she tilts her face toward the sound of the Doctor's voice anyway. "You figure it was something like that with you and... well, that other you?"
The silence stretches on just long enough that Yaz considers opening her eyes anyway to see what's happened, but before she can, the Doctor says, "How do you mean?"
"You know, some tiny decision. Flute or clarinet. Butterfly flapping its wings and all that and suddenly you're a ginger bloke with an at-- with even more attitude," Yaz amends.
This time the Doctor tromps around the TARDIS console, punctuating the silence with unidentifiable -- still unidentifiable, after all this time -- clicks and creaks and pings. "Sorry," she says at last. "You reminded me of -- anyway, short answer is, I don't know. Well, nobody does, really! Can't say I haven't tried controlling the regeneration when it comes up, but it never really turns out, and of course there's not really anyone -- anyway."
"Anyway?" Yaz prompts when it seems nothing else is forthcoming.
The Doctor sighs. "I suppose -- well, I can't say for sure why me and not him, but something about this me feels... right. Like I've started picking up the music I heard from -- so many amazing people. Like I was never quite in the proper key to do it before. Maybe the ole DNA figured I was finally ready to try."
There's a particularly deep, melodic clunk as the Doctor finishes up at the console, and the timbre of the TARDIS hum changes to one Yaz can identify: mapped wormhole ahead, set cruising speed.
"Do you still remember any of the songs you learned, playing flute?"
She was never a star student, but she riffles through muscle memory and half-remembered sheet music anyway, and comes up with a still-vivid fragment. As the TARDIS passes into space outside space outside space, Yaz whistles the theme from Symphony from the New World into the velvet gullet of the wormhole.