AN: Welcome to my 2018 Christmas fic! Here be fluffy romance and friendship, an AU where everyone is happy and not much hurts, and a story in which Mac actually has a detailed plan.

This is a touch early, as I'm going on a roadtrip with my family for the next couple of days, and thus might not have internet access reliable enough to post this.

I will, however, try and get a chapter up every single day until Christmas!

This is mostly a Mac/Beth fic (and works as an introduction to her if you haven't read my other fics in which she appears), with some James MacGyver/Ellen MacGyver, some Jack/Diane and a touch of Riley/Bozer, as well as a surprise (sort-of) and some background ships featured in my other fics.

Title comes from the Christmas carol The 12 Days of Christmas.

DECEMBER 14th

MACGYVER'S RESIDENCE

PASADENA

Angus MacGyver, twenty-eight year old JPL engineer, put his Swiss Army knife away as he finished curling the ribbon on the present sitting on his desk (it was wrapped in cheery Christmas paper, of course – this paper had a pattern of cute reindeer on it).

He picked it up very carefully and examined it closely for imperfections, before setting it down again and grabbing his favourite brown leather jacket from where it was hanging over the back of his desk chair and shrugging it on.

(There was no need for him to put it on, not really.)

(It might be December, but he did live in sunny LA.)

(Besides, he was just going next door.)

(But Bozer said that the leather jacket was his 'signature piece' and that he looked really good in it, so…)

(His grandfather had always said that a gentleman should dress as the best version of himself to impress a lady.)

Mac shook his head a little as he picked up the present and left his bedroom.

He was even more nervous than he had been when he'd lost that bet to Bozer and had to ask Darlene Martin to Prom.

Which was ridiculous, because he definitely wasn't fourteen anymore, and the intended recipient of this gift had pretty much nothing in common with Darlene Martin, aside from being female and very, very pretty.

(Darlene – the prettiest girl, and one of the most popular, at Mission City High – had only been nice to him so that he'd do all the work in chem class, as well as all of her homework.)

(It was kind of embarrassing, actually, how easily fourteen-year-old him had been fooled by a pretty face and pretty, well, other things.)

(He was pretty sure that this gift's intended recipient would actually like him less if he wasn't weird and nerdy and didn't have algorithms for nearly everything and a mathematical proof for the plausibility of the existence of Santa Claus.)

His BFF/roommate/tenant, Wilt Bozer, FBI forensic accountant extraordinaire, waved sleepily at him from the kitchen, still in his pyjamas.

(It was 7:30 in the morning.)

'Morning, bro…' Bozer noticed the gift in Mac's hands, and instantly, he was an awful lot more awake. Mac groaned internally. Bozer was family, and like any family, he was far too interested in Mac's business, especially his love life. 'That for The Doc Next Door?'

(Riley Davis – Mac's JPL co-worker, though she was in software and he was in hardware, and another member of the family – had disapproved strongly of Bozer's original nickname for his and Mac's next-door neighbour, The Girl Next Door.)

('She's a grown woman with a medical degree, Bozer!')

Mac nodded. His ears were definitely turning pink under his hair.

'Uh, yeah.'

Bozer smirked, before making a face of confusion.

'It's December 14th, we've still got twelve days 'till Christmas…' He actually looked a little panicked. 'Has she changed her plans for Christmas? Is that why you're giving her her gift early?'

(Bozer took Christmas – more accurately, Christmas dinner – very, very seriously, so any kind of disruption to his careful plans elicited panic.)

Mac shook his head, raising his free hand reassuringly.

'No, she'll be at the Christmas party, Boze.' He paused, looking a bit sheepish. He was well-aware that he was really going overboard, but… 'This is, uh, just her first Christmas present...you know, twelve days of Christmas? Not that today is actually the first day of Christmas, but for my purposes…never mind.' He trailed off. He was well-aware that he could be annoyingly pedantic at times. 'I have a plan.'

Despite common preconceptions, the twelve days of Christmas actually start on Christmas Day, not end.

But for my purposes, starting on December 14th, the first day of the not-actually twelve days of Christmas, works better.

Bozer, meanwhile, looked sceptically at his best friend.

'You have a plan. A detailed plan consisting of twelve different Christmas presents that I guess you've already made?' Bozer sighed exasperatedly and muttered something about trying so hard to raise them right. 'And that involves finally asking her out on the twelfth day?'

(In Bozer's opinion, Mac should have asked The Doc Next Door out months ago.)

(It was an opinion shared by the rest of the family.)

(He didn't even have the excuse of lacking in opportunity, since she lived next door.)

Mac just nodded a little sheepishly.

I will be the first to admit that I am not good with plans.

I'm really more of an on-the-fly kind of guy.

But that doesn't mean that I'm not capable of one from time to time, especially given the right incentive…

Bozer smirked.

'She's rubbing off on you!'

She likes plans.

And to-do lists.

And is a firm believer in fully utilizing day planners, organization and being prepared in general.

Apart from the obvious, she would have made a much better Boy Scout than me.

Mac walked out of his front door, up the front path, and then a few feet along the sidewalk to the next front path, and walked down that.

(He and Bozer lived in a townhouse at the end of a row.)

Seriously, MacGyver, get a grip.

You are a grown man.

You disarmed bombs for the Army for eight years, including five years as a member of Delta Force.

You're as certain as can be about something like this that she does really, really like you too.

Mac raised a hand and knocked on his neighbour's front door.

The door opened to reveal The Doc Next Door, Dr Beth Taylor, a pretty, sweet-faced brunette woman who looked to be in her early-mid-twenties (though Mac knew she was older, also being twenty-eight). Her hair was already pulled and pinned back into a neat ponytail and she was already wearing her scrubs.

(She was an attending ER physician at Huntington Hospital nearby, and her shift started in an hour.)

Beth smiled up at him.

'Good morning, Mac.' She took in the Christmas present he was holding, and her head tilted to the left, brow furrowing. 'Have you decided to go on a last-minute Christmas vacation?'

He shook his head immediately.

'No, uh…' This was hard to explain. He was probably being awkward. Maybe he should have thought it out better. '…um, just open it, please?'

Now looking very curious and a little less confused (he had a feeling that she might have an inkling as to what was going on – or even more than an inkling), Beth took the gift from his hands and methodically began to unwrap it, undoing the bow, before carefully peeling off each piece of sticky-tape and removing the paper.

(He couldn't help but smile a little wider, fond and amused.)

(Of course she was one of those present unwrappers.)

She then opened the cardboard box that was inside, to reveal the carefully-packed mechanical partridge inside.

'Oh…' It was very much a noise of realization. She glanced over at him, smile widening, cheeks pinking adorably. 'You're starting the twelve days of Christmas twelve days early?'

He nodded.

'Uh, yeah.' He gestured at the mechanical partridge that he'd carefully constructed using bits and bobs he'd had in his stash of what everyone else called junk that filled the garage and attic. 'It's for your pear tree, to scare off real birds when it finally bears fruit.'

He put his fingers in his mouth and let out a few bird-call-like whistles.

The mechanical partridge burst into life in Beth's cupped hands, several LEDs lighting up and the wings flapping madly.

It made her whole expression shift into one of almost childlike wonder, and she gave a little laugh and glanced up at him again when the bird stilled, looking very impressed.

Her cheeks were very pink, too.

He smiled back, the expression on his face part-smug-smirk, part-shy-smile and part-besotted-grin.

I admit that the classic Christmas carol influenced my choice of bird, but I'm not just blindly following the song, I promise.

What in the world would Beth do with leaping lords or a dozen drummers?

Besides, romance is not one-size-fits-all. It requires customization, since it's all about showing the other person that you're thinking of them and that you care enough to know and remember and consider things both big and small about them.

For example, my mom's favourite perfume is a vanilla scent that came from this little perfumer in Paris that my parents stumbled upon on their honeymoon.

Dad bought it for her every anniversary.

Fifteen years ago, they stopped making it, so Dad analysed it by gas chromatography-mass spectrometry and worked out how to make it himself so he could still give her a bottle every anniversary.

Mom says that that's the most romantic thing anyone has ever done for her.

So, yes, there's a story here.

ELEVEN MONTHS AGO

As he started to bounce up and down on his back deck on a brand-new pogo stick (it'd still been in the box) that he'd picked up for a steal from a garage sale down the block, Mac glanced into his neighbour's backyard.

(The fence was only about four and a half feet tall in the deck areas; it did, however, reach six feet between the lawn areas.)

For the first time in three weeks, the yard wasn't empty.

(His previous neighbour, retired CalTech Physics professor Alexander Oorlov – who loved to bicker with his best friend Victor Levkin, enjoyed hearing about Mac's various experiments and work and loved The Price is Right – had recently moved into a nursing home.)

Instead, there was a petite woman with light-brown hair wearing jeans and a striped long-sleeved T-shirt crouching by the flowerbed on the far side.

She had a pot of purple-blue water in a saucepan next to her, with pieces of red cabbage in it. As Mac watched, bouncing all the while, she ladled some of the water into a jar, then added some soil.

He was so surprised that he wound up speaking without thinking.

'Are you testing the soil pH using red cabbage?'

The woman whipped around, startled, but her hands remained steady and she didn't drop the jar, or the chopstick she was using to stir its contents.

She was young, probably a couple of years younger than him, and very, very pretty.

She also didn't seem to think he was rude or crazy, and just nodded, as if this was a normal conversation to be having with your neighbour, like a chat about the weather.

'Yes, I need to ensure the soil is acidic, for the pear tree my parents gave me.' She gestured at the sapling in a pot sitting on the deck. It had a blue bow tied around the trunk and there was a cardboard pear-shaped label attached to it. 'I don't own a pH meter or pH paper, and they're expensive and not the easiest to obtain, so I improvised.' That made him smile a lot wider than it probably should have. She tilted her head to the left. 'Why are you jumping on your deck on a pogo stick?'

She sounded and looked a little bemused, but not judgemental. In fact, she sounded rather curious, like she couldn't come up with a good reason for a grown man to be jumping around on a pogo stick, but really, really wanted to hear the good reason.

That was surprising.

(Though maybe it shouldn't have been, considering how she'd responded to his question.)

A lot of people thought he was completely crazy.

(Even Bozer, Riley and Jack, who were family, even though they weren't blood-related, generally responded to his weekend or after-work experiments with affectionate tolerance and a lack of interest in the details. They thought he was crazy too, but they loved him, crazy and all, and made an effort to show it by doing things like buying him garage sale junk or paperclips or duct-tape or gift cards to appliances stores for his birthday and Christmas.)

Not many people were actually interested in the nitty-gritty science.

His parents were, of course (his dad was a workaholic DARPA engineer, his mom a dedicated and passionate high-school science teacher – it wasn't exactly surprising that he'd turned out the way he was). A good number of his co-workers at JPL were too, as were Frankie, Smitty and the rest of his MIT buddies. Mr Ericson, his mom's colleague who'd taught Mac in the 8th grade, and Valerie Lawson, one of his students who was every bit as brilliant as Mac was at that age, were always into the scientific details too.

And maybe, a little voice in his head said, your beautiful new neighbour.

(Mac told it to shut up.)

'I'm, uh, doing some experiments on the changes in the spring constant of a pogo stick spring with wear and tear, so I need to create some wear and tear, so…'

(He had no idea what the potential applications for the information were, but it might come in handy one day.)

(Besides, he just liked knowing things.)

He gestured with his head downwards, towards where he was still bouncing up and down on his pogo stick.

He hadn't realized that he was still jumping, and realized in the same moment that it was probably awkward, rude and weird, so stopped, balancing on the stick and leaning against the fence instead.

His new neighbour tilted her head to the left a little again, still looking very curious.

'Interesting.' She sounded like she definitely meant it. 'What have you found? Are the changes linear? Or exponential?'

The little voice in his head got louder as it pointed out, yup, she's definitely into the nitty-gritty science.

Ten minutes, one diagram and three equations passed over the fence, and a slight detour of the conversation into the elasticity of his deck later, Mac realized that he had absolutely no idea what his new neighbour's name was.

They'd apparently gotten so caught up in the science, they'd forgotten about manners.

(It was a bad habit of his. He was trying to work on it. He didn't think it was going very well.)

Now, how was he going to rectify the situation?

'…there's a story behind that variation in elasticity that's going to oblige me to be professionally concerned about your wellbeing, isn't there?' He looked a bit confused, and she looked sheepish and somewhat awkwardly raised a shoulder in a way that seemed apologetic. 'I'm a doctor. Attending ER physician at Huntington, to be precise.' Even if she was a couple of years older than she looked, that was very young to be an attending physician already, though he admitted that given their conversation, he wasn't terribly surprised. He was young to have graduated from MIT (his mom had strongly encouraged him to take college classes when he was still in high school, including during the summer, partly to combat his boredom, which had been empirically shown to have unfortunate consequences, such as the loss of Mission City High's football stadium, so he'd graduated in only two years) and served in the military for eight years, then worked at JPL for one and a half. He'd been young for being in Delta Force and was one of the youngest engineers at JPL. Birds of a feather recognized one another. His new neighbour stood up on her toes so that she could raise a hand over the fence to shake his. It was an awkward motion, since she couldn't have been taller than 5'2''. 'Beth Taylor, I'm moving in tomorrow.' She paused, smile turning more sheepish. 'I think I should have mentioned that earlier…'

He smiled sheepishly back at her as he shook her hand.

'Angus MacGyver, JPL engineer.' An ah look crossed her face; he suspected that she'd treated a co-worker or two of his for a weekend experiment gone awry. 'Please call me Mac. Welcome to the neighbourhood.' He paused, expression turning a touch more sheepish. 'I should also have mentioned that earlier.' His smile turned more wry, and he lifted a shoulder. 'I won't tell if you don't?'

That made her giggle, and she nodded, smile widening.

'Thanks.'

THE PRESENT

Mac and Beth finished attaching the partridge-scarecrow to her pear tree, and she looked up apologetically at him as they headed back inside.

(They both had to get ready to leave for work.)

'I only got you the one Christmas present, I'm afraid…'

He just smiled back at her, pausing in his steps and looking her in the eye.

'A, it's a gift, not an exchange.' His voice softened a little, even as something a bit more intense appeared in his eyes. 'B, you've already given me plenty.' After a very brief moment of the two of them staring at each other, something a little weighty there, his smile turned more wry, joking. 'I'm pretty sure I owe you a few.'

She gave a snort of laughter, then poked him in the bicep firmly.

'It's not about keeping score; we should stop.' She paused and amended the statement. 'Well, stop letting the score influence our actions.'

With a memory and a brain like his, not keeping score was near-impossible.

It was surely the same for her.

Still, it was a good principle.

'Deal.'

Meanwhile, as he dug into his breakfast of Honey Nut Cheerios, Bozer texted a couple of very interested parties a report of what he'd seen that morning.

The very interested parties were Jack Dalton (ex-CIA, former Delta Force, now a mechanic and Mac's other BFF, second dad and Obi-Wan Kenobi to his Luke Skywalker – they'd met in Afghanistan, become close friends after a rocky start and had wound up on a Delta Force team together for five years) and Riley Davis (Mac's co-worker who, in a coincidence that even Mac thought was highly improbable, was also Jack's ex-girlfriend's daughter – stuff had been rocky between Riley and Jack for a while, since he'd walked out on her and her mom after beating up her dad for throwing Diane Davis around, but things were all good now).

(Bozer was also glad that things were all good between him and Riley now, after his embarrassing and honestly kinda jerky treatment of her at first – 'hello, future girlfriend' was a terrible thing to say to a woman on meeting her for the first time. Jack had given him a much-needed kick up the ass, the lesson reinforced by several others, and he and Riley had become friends. Real friends.)

(Which was great, because Riley Davis was an awesome person.)

(She was strong and brave and had a really, really good heart hidden under layers of sass and sarcasm. Riley loved the people she considered family fiercely, and would do anything to protect them. She'd gone to jail for her mom, and survived things that Bozer was pretty sure would have broken him. And she had great fashion sense, unlike a couple of vets Bozer knew, was really good at video games, and had excellent taste in burgers.)

He got two replies almost immediately.

FINALLY.

The other one was just a string of emojis expressing the same sentiment.

(Jack liked emojis too much.)

Bozer, however, couldn't exactly blame him for the excitement.

They'd all reached the point where they were all seriously planning an intervention.

(Which was tricky, since locking them in a room or an elevator or something wasn't going to work, because Mac could escape from anything in minutes.)

Mac and Beth should have reached their first date months ago.

But, this was what happened when you had a pair of somewhat socially awkward former child prodigies with lingering self-esteem issues and a depressing romantic history (on Mac's side, anyway) who were hence too scared to rock the boat a little and make the first move.

(Even though at this point, it'd be hardly any boat rocking and only the good kind, Bozer thought.)

Jack's emoji chain was soon followed by another message.

Wait, did you say he's got a plan?

More emojis, now with a panicked flavour.

We sure this is a good thing?

Even more panicked emojis.

You know our boy and plans don't go well together!

AN: Did you guys enjoy that? Do you think I did a decent job adapting canon backstories to this AU? There'll definitely be more threads from canon coming into this universe; those who are familiar with my works probably know that I really like the idea of the butterfly effect and universes being different, yet also similar.

See you guys in about 36 hours!

Tomorrow's gift for Beth: Two Modified Toasters.