A/N: Has this been written yet? I feel if it has not been written yet, then it's very painful and egregious a crime it's taken us this long as a fandom to get to this point. If it has, then I hope to add to the fun with another potential take on the concept; if not, then I offer this as a group repentance for the severity of our sin of not jamming these two particular 1980's sci-fi properties together.

3340 words; shout out to the Clara's Diner Discord for bringing this to my attention, as well as art by ceciditangelo on tumblr; is definitely going to be multiple parts, because how the hell could all this be contained in one sitting other than poorly; just trust me when I say that this is going to be a wild ride

Back to the T.A.R.D.I.S.

One

St. Luke's was a boring place to grow up, in Bill's professional opinion.

She was stuck there, as many are with their hometowns. It wasn't as though it was hostile to someone like her—for being a Black lesbian in a new town in the south of England, her existence was disturbingly rather charmed—there was merely a sort of dull monotony simmering just under the cheery veneer. Once one ventured further than the summer festival and local brewing scene and the interfaith celebration of the village mosque's grand opening, it all seemed painfully trite. She wasn't going to go around complaining, because things could be plenty worse, but she also knew that the semi-rural suburban life was stifling; like a well-meaning aunt, it treated her with kindness and respect while at the same time was baffled at the fact she wasn't happy despite having everything she supposedly needed right there.

Riding down the street on her bicycle, she went on her normal route, waving to the usual suspects as she encountered them. She was sure that none of them knew the ache she felt in her very soul, but that mattered little. All they knew was that she was Moira's foster girl, heading off to the part-time job she'd had since secondary. Other jobs had come and gone, yet this was the one constant, despite people's worry as she came to a stop next to a workshop and walked her bicycle in—was she good for her employer or was he corrupting her into becoming a disruptive influence? No one wanted to know.

"Hello? Doctor?"

She heard a vaguely Scottish noise and knew that her boss was in. Well, yeah, he did pay her to tidy up around the place, but he was more than just her employer. Doctor Basil Brown—referred to as the Doctor by most—was a middle-aged widow, a scientist, a nut, but most of all, he was the same as her. He knew the same rural-suburban blues as Bill, except for him it was because he grew up in Glasgow, yet had moved to St. Luke's for his wife's position as the head of the district's library network. It had been years since she'd passed on, yet he was still just as stranded as the young woman who'd merely lived there her whole life. They were both oddballs and their differing ways of being different seemed the ultimate compliments to each other.

Carefully toeing around the workshop, Bill eventually found the Doctor underneath his junker car, one he had been attempting to fix up and retrofit for ages at that point. It was honestly one of the first things she remembered him doing, back when she was a small child and he was newly, broodingly single. She hooked her foot on his and pulled him out, the creeper he was laying on moving with ease.

"What was that for?" he asked.

"I didn't hear a proper hello."

"I don't keep you around because you're deaf and therefore can't hear when I say hello or cuss at something dropping on my toes," he snarked. She folded her arms across her chest and he shuffled himself back underneath the car. "That'd be a poor reason to keep someone around anyhow."

"Would you keep me? If I were deaf?"

"As long as your brain's not made of mince, I don't care," he groused. "How was your date last night?" Ha, smooth, changing topics.

"Nice enough," she replied. "I think Heather and I really like one another. Might make it exclusive."

"She'd be an idiot not to—your brain stem's working and you're about the only person in this place her age that wouldn't mind moving back to Leeds with her. Make the move before what's-his-face does and your bi-gal goes bye-bye. Don't want a repeat of Penny now, do we?"

"You're a tit, you know that?" Bill began to browse around the shop, seeing the progress that the Doctor had made on all of his projects. There were some that she knew all the details for, some she didn't understand thanks to a (desired, mind) lack of several PhDs in Useless, and one she was not allowed to know about. That one sat in the corner, a tarp over it, looking ominous, like a murder-box just waiting to pop out at any moment. "How are the paychecks coming along?"

"Sent the one out yesterday while you were sitting that test," he replied, "but I haven't heard yet that it was received. You know… the low-power laser pointer that won't blind a bloody pilot if it accidentally falls into the hands of a terrorist or a twelve-year-old."

"Ah… I thought something was missing." She found herself staring at a photo on his workbench, of him and his wife on holiday shortly before they'd moved to St. Luke's. River was a vague memory to Bill, though not vague enough to where she didn't recognize the woman from life. "You ever think about getting yourself out there? Doctor Song's been gone a long time."

"I've met the eligible ladies of St. Luke's and the surrounding parish—makes just about anyone not want to date again," the Doctor claimed. He came out from underneath the car for good this time and saw where Bill was standing. "No one's caught my eye since her, you know."

"I know—it's just worth a shot. You never know what might happen."

"…which is precisely why that sort of thing is off the table," he said resolutely. He wheeled himself out from under the car and grabbed for a rag, wiping his hands free of grime. "There wasn't another like her—you can understand that."

"What I understand is that if I do make it exclusive with Heather, I might move, and then what'll you do?" Bill saw the Doctor's face darken, knowing she hit a potential nerve. "I would rather move to Leeds while knowing you've got someone else watching after you."

"I'm a grown adult," he groused. "Stop sounding like I can't get on without you."

"...and when was the last time you organized your own shop?" she posed. He scowled at that.

"You always get to it first—there hasn't been a need for me to in a long time."

"I've been doing it since I was twelve and I don't think it had been done even once since you moved in," she reminded him. He knew she had him there and he decided to drop it. "You don't do well alone."

He shrugged at that. "How would you know?"

"I spent the entire first week I was employed here mucking out the kitchen," she reminded him. He grumbled incoherently at that, passing her a broom instead of replying verbally. She took it, knowing that there was worse ways for him to react.

Eventually, the shop was tidied and the Doctor was making dinner. He refused to let Bill leave until after she had eaten and handed over her latest essay draft ready for him to pick apart over the course of the evening. It was dark by the time she cycled home, pulling her bike into her tiny garden once the streetlamp flickered on.

"How was work, Billie?" her neighbor asked over the low fence. The older woman was getting ready to go in the house, the bugs having come out en force. "Is Basil doing alright?"

"Doc's doing just fine, Ms. Bush," Bill replied. She then had a thought and paused as she was securing the bike lock through the frame. No… wait, possibly…? "Say, Ms. Bush… you always ask about Doc Brown whenever I come back from his place."

"I'm concerned about everyone in St. Luke's, and you so happen to be the one who interacts with him the most," Ms. Bush shrugged. "Is that so bad?"

"It's not… it's just…" Bill stood and looked at her neighbor—the same woman who had lived next to her for her entire life—and wondered if she should make the attempt. "You know how I'm seeing someone?"

"I am." She was careful not to say it too loudly or precisely, in case Bill's foster mother overheard.

"It's making me think about my life after the Doctor… his life after me…"

"Not a word more—the answer is no, and you can stop thinking those thoughts, young lady," Ms. Bush scolded teasingly. "You've got a better chance hooking Doc Brown up with a young thing just off the Emmerdale set than with me. Scotsmen aren't my type."

"Never know until you tried," Bill smirked. She shrugged as she went inside the tiny house, her foster mother already sitting in front of the telly. "Moira, I'm home."

"Did you eat?"

"Yes—the Doctor made pad thai."

"Good on him—if he wasn't still mourning poor River, I'd think he was making moves on you," Moira stated. "There's a bit of salad left if you're feeling peckish later."

"Thanks." Bill went up the stairs and calmly shut herself in her room. Who ate salad when peckish? Why would the Doctor, of all people, make moves on her? When should she tell her foster mother that she was unequivocally immune to romantic male charm? How come the conversation never went to asking how she was doing for once? Christ, it was bloody boring, like a daytime soap with the lowest-of-stakes writing ever. She looked at the photo on her nightstand—her mother, smiling to the side in the blown-up background of one of River's old photos—and sighed heavily… bloody soap fodder for sure.

She went to sleep that night dreaming of a flat of her own, with her girlfriend cuddled in her arms while a cat was readying to insist on one of them feeding it. The Aire was outside their window and the sun warming their tiny sanctuary, creating a cozy, blissful atmosphere.

Except, as she dreamed on, there was a feeling of dread that permeated against the bedroom window, that was threatening underneath the covers as they shifted positions and began to lazily kiss. Bill positioned herself atop Heather and began to leave kisses along her pale neck, murmuring lowly. It was the beginning of a dream she had dreamt many times before, of where they got to live as girlfriends and idiots in love, only now… the dream was was interrupted by a pounding on the glass windowpane.

It was the Doctor Basil Brown, and he looked lost as a puppy. Soon as Bill realized this, everything seemed to come crashing inwards, with the walls closing in, the light from outside fading, and a murky goo bubbling up to swallow up the blonde woman beneath her, then herself.

Bollocks.

Not too long after her dream, Bill woke up to a weird text.

'get down here soon as you can manage. donuts provided.'

After checking the text and the time, she realized that the message was already an hour old, despite the fact it was still fairly early. She groaned, knowing that meant that it was Experiment Day: an eclectic sort of event where Bill became a guinea pig or watched the Doctor become a test dummy while she wrote down the catastrophic results, and it was bound to be a weird one if he was attempting to contact her before the arse-crack of sunrise. The early ones were always some of the wackiest, for some reason she rather stay unknown to her.

Shower, clean clothes, and after gathering all of her things in a bag, Bill snuck out of the house without waking her foster mother. Not even Ms. Bush was up, which was interesting considering the woman was often taking a very early morning coffee on her patio while checking into her ever-constant work. She took her bike and made the quick ride over to the Doctor's, finding that he was already in the middle of Experiment Mode.

"Ah, there you are," he said, not even bothering to look and see who it was who walked in the door. He was underneath the cloth that covered the box in the corner, a moving lump of fabric. "Donuts are on the bench."

"Doctor, it's not even six in the bloody morning."

"Yes, I know—the sun won't rise for a bit."

"...and why is that so important?"

"I never said it was important."

"What did you get me up this early for then? Shiggles?"

The Doctor finally uncovered himself from the sheet and looked over at Bill, grinning wildly despite the goggles that covered his eyes. "Sunrise is going to be extremely important here. We're going to need a power surge."

"You're deploying the roof's solar panels?" she wondered. "The experimental ones? The ones I thought were way too dangerous to use at full capacity due to how they metabolize energy…"

"They are, but that's not important," he replied, flipping up his goggles up to his brow. "What is important is that we have a window to act and that time is almost upon us. If we don't succeed in this experiment within the next few days, we won't be able to for another few months, and I'd rather start making attempts soon as possible. Too much energy and it explodes; too little and it won't do what it needs to."

"Do what?"

The Doctor pulled the sheet off the boxy thing and showed Bill his experiment. She wrinkled her nose at it.

"A police box…?"

"Not just any old police box, but a TARDIS—short for Time and Relative Dimensions in Space—a time machine. I plan on this being my final piece."

"A… time machine…?" she frowned. "Why, of all things, you want to build a time machine?"

"Ever since River died," he explained solemnly, "I have been aching to see her one last time. The science is sound—if unconventional—and I know that I can go back to before she was sick, see her again, and then I can retire in peace." He seemed sad; the pain of her loss seemed to be a dull ache more than anything these days. "I plan on using this to go back in time by thirty years, to before her and I married, before she even went by River Song. The plan is for you to come along too, as my assistant."

"Wait… thirty?!" Bill gasped. She then grew quiet, staring at her mentor uncertainly. "That was before I was born."

"It was—glad you can still do maths."

"No… there was someone else alive in this village thirty years ago that isn't anymore." She bit her lower lip, hesitant to say it out loud. "Are you saying that with this, if I go with you, I can see my mum?"

"I'm saying that with this, we are no longer bound by the linear constraints of time and space," the Doctor grinned, showing Bill how wild his emotions had truly become—he was almost feral in his excitement. "With this, we can see more than just your mum. We can see things as they used to be, things that have long since left this world behind..."

Bill's breath caught in her throat. "Does this mean that we can… you know… stop her from…?" Her eyes grew very sad as she looked away, the Doctor knowing exactly what was wrong.

"No, it's not like that, Bill," he said solemnly, mood changing sharply. He placed a hand on her shoulder—it was a rough thing, and not just for her. "We can't change the past. There are things we can do that would completely change the course of history, and not always for the better. You must promise me that if we succeed in this experiment, that you won't actively go and change anything."

"I'm not talking a big thing like changing Hitler," she defended. "Though that would be nice…"

"As nice as it is, some things are fixed points," he stated. "Some things have to happen, for good or for bad. We would like to go back and change Hitler, but we don't know if he was the least of the evils we could have had—with no way to prove there could have absolutely been a better outcome and not make way for a worse one, the stakes are too dangerous."

"That's a bit wrong to think of Hitler as the lesser evil," she said, scrunching her nose.

"I'll be the first to admit that, but you gave me a handy way of explaining things in a very concrete way," he replied. "No changing the past, even if it would benefit us as individuals or us as a species. We are scientists conducting an experiment that might cost us our lives."

"You're the scientist—I'm your part-time help."

"You know what I mean." He stuck out his hand. "Shake on it?"

She stared at his hand and hesitated. It was dangerous, but it was going to be the dangerous opportunity of her entire life, getting to potentially meet her mother for the first time in her conscious existence. There was even the chance to see the late River, and she could pull her aside and let her know that she was keeping her husband from accidental electrocution and malnutrition in his middle aged widowhood. St. Luke's would be at least a tiny bit different, the entire world would be different…

...everything would be monumentally different if she could speak to her mum at least once.

Bill placed her hand in Basil's and shook it heartily, with his grin turning into a giggle. He broke the handshake and wandered off, going to a nearby cupboard where he began rummaging around in. After pulling out some clothes, he threw them at Bill.

"Here, wear this!" the Doctor instructed. He began to strip in front of the cupboard, pulling items on as he pulled his normal ones off, not caring that his young friend was there. Bill wrinkled her nose and stared at the clothes in her hands.

"…what the hell is this? It's not protective gear."

"Our disguises—can't stick out too much," he explained. "I was there thirty years ago, remember? A lot of this stuff is mine or was River's."

"It's kind of neat."

"It was a fashion disaster, but then again, what decade wasn't, isn't, or won't be?" He put the yellow jacket on over a red silk shirt and glanced at himself in the mirror. "Still a decent fit—I'm surprised. Hurry up, Bill, or we'll miss our window!"

"Hold up Breakfast Club, I'm getting there," she scoffed. She opted to take just the jacket, since she was certain her charity-shop tank-top-and-jeans combo originally dated from thirty years prior anyhow. After admiring how it looked on her in the mirror, Bill found that the Doctor was pushing a pair of aviator sunglasses and an old Casio watch into her hands.

"Accessories," he claimed. "We're going to need to make sure that our watches are synced while we're there. We will only have three hours while we're there to do everything we need to before the TARDIS reverts back to this time period."

"...but, Doctor Song was from the Midlands. We're nowhere near the Midlands."

"Thirty years ago, River was already living here under a work-study program," the Doctor explained. "She moved around between here, London, and Glasgow for a long time, and before her and I settled here permanently, this building had been abandoned from 1956—it's the perfect situation."

"You're mental," Bill stated. "Even if we do go back in time, what's to say that she will even be in town? She could be visiting her parents! Off with friends! With someone else…"

"I would not have picked this time if I was not confident in the fact that she would be there and we wouldn't explode in the process," he said. "This is going to be an experiment that is worth doing, if because if we can meet these people, even for one moment, then it will have made all the difference in the world."

"...and if we don't…?"

"Then at least we can say we tried," he said before putting on his own sunglasses. "Sunlight's coming—to your stations!"

Bill began helping the Doctor with plugs and wires and switches and dials, as she was used to on Experiment Day. She hoarked down a couple donuts while she did so and then shoved herself first into the TARDIS interior. It was a bit roomier than she expected, which was very welcome as the Doctor came in after. He was a skinny bloke, yet he still took up plenty of space.

"Alright, let's go!" he cackled. He lit his watch and began a countdown, marking the precise second dawn was to be upon them.

At first, it seemed as though nothing was happening, but as the Doctor got closer and closer to the number one, Bill noticed that the box was beginning to shake. With each passing second, the Doctor's ability to contain himself slipped further and further from reality.

"Five, four, three, two, one! This is it!" His glee could not be hidden—it was working.

Bill's stomach lurched. Oh God… it was working.