A/N: as stated in the description, this fic will focus on the pairing Mikaela/Optimus Prime, and the events that occur as a result of twenty-first birthday shenanigans.

These 'events' being (eventually) of a sexual variety, so if that isn't your cup of tea, this is your warning. Also, I may have a small (or not-so-small tbh) infatuation with big diesel trucks which, well... does not exactly make me any less fascinated Optimus Prime's alt-form... (like he wasn't already super hot WITHOUT having a gorgeous alt-form). So, disclaimer- just in case it was not already implied strongly enough, this story will eventually contain fornication between said semi-truck and a human.

It is also a part of a series; if you wish to check out the fanfiction that precedes this one (called Redline), you will find it under this account, but it is not altogether necessary to read that one before you read this. :) So, without further ado... and before I can regret this any more than I already do...

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E-Brakes On

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Part 1

~One month before the events of Dark of the Moon or something

Summer 2011 brought with it the most shatteringly hot afternoons on record. In the city, the heat was so extreme that you could cook a four-course meal right there on the sidewalk if you'd tried—the roadways were turned into seventeen long klicks of sheer sizzling hotness from one side of the place to the other. The miles-high skyscrapers did nothing but block the wind, and their millions of mirror-glass windows sent down a thousand more cubic tons of geothermal radiation onto the already-suffering citizens.

It was pure hell on earth, and on days like this, there was nothing for it. One had to hit the road.

It was that sweet smell of pavement, the rush of the wind in her hair that was so addicting. It was the pleasure of the open road, the promise of not stopping 'til the sun went down. The intoxicating high of it was rivalled only by the speed of her Plymouth Fury nicknamed Christine's pistons and the fires burning inside of her internal combustion chambers as Mikaela slammed that pedal to the metal and the cherry-red muscle car shot forward so fast you'd get whiplash if you tried to watch it fly by. It was freedom, it was fearlessness, and moreover, it was Friday.

God, yes.

Today was the day that Mikaela had been waiting for. It was not just a regular Friday—even though Fridays were always her favorite day of the week—but this Friday in particular happened to be Mikaela's twenty-first birthday.

And it was not every day that a girl turned twenty-one. A hell of a day it had been already, too—she'd spent the morning in the shop with Cal and the boys, who had picked out a large, incredibly rich chocolate cake for her that had been decorated with a badly-iced picture of what was obviously supposed to be a depiction of good old Christine. After a slice and a complimentary cup of hot, strong coffee, she'd got to work, only to be let off early by Mike, who had given her his usual smoky grin (he had a habit of walking around the place with a honking pipe sticking out of his mouth), and had told her that she was free to go, so long as she made sure to get good and drunk tonight.

Of course, Mike was not allowed to know where exactly it was Mikaela was headed. Even Cal, who thought he knew where she was going, did not know the exact details, not that it bothered him much—Cal had always had a lot of faith in Mikaela. Mikaela supposed that there were only so many times you could take your preteen daughter along with you as your partner on a car-jacking without developing a very strong bond of trust with her.

"So, when am I going to meet this guy?" was all that he had asked as he watched her head out the door at full speed, but she knew that he was mostly just kidding around. They'd already had that awkward father-and-daughter 'new boyfriend' conversation a couple months ago, and Mikaela had made it quite plain that it was mostly just a casual thing. This information had touched a nerve for Cal at first, but she had assured him that it was not because this 'guy' was not taking Mikaela seriously—but because he happened to have this unbelievably-crazy-ass time-consuming career that was very important to him and usually demanded almost all of his energy except for the occasional weekend.

She also made sure to tell him just how far out of the city this guy lived, though of course without making it sound like he lived in the absolute middle of nowhere or something bizarre—he's a suburbs dude. Lots of money. Big house. Crazy parties—I'm kidding! We don't party. His house is super boring except for the pool and there's always a chaperone. His uh, parents are always around. And you'd like them, they're super… um, interesting was pretty much how she'd described it.

This was enough to satisfy Cal. Plus, if Mikaela was happy, so was he—and Mikaela recognized that Cal (even though he would never admit it), was sort of impressed by her information on mysterious-boyfriend thus far. Because, as a young woman who was just a couple years out of high school and who had spent the last two years with a boy who had had his share of problems (Sam), problems such as very noticeable levels of immaturity and a major lack of self-confidence, it was rather unexpected that she should land herself such a mature-sounding, older guy… or at least that was how it had been when she'd described this so-called mr-we're-totally-not-really-that-serious but-he's-still-super-respectful-and-really-good-looking to Pat, back when Mikaela had found herself the subject of said Pat's full attention and seemingly-endless tirade of boyfriend-related-questions.

This Pat came in the form of one super-attractive almost-fifty-five year-old woman whose sandy-blonde ringlets fell all the way to the leather-studded belt (which did absolutely nothing to hold up her painted-on jeans) who was the brand-new addition to the Banes household. She and Cal had been dating for nine, going on ten months now, and Mikaela didn't mind her. She was nice, she absolutely adored Bonecrusher (who loved her very much back), and if anything, it made her disappearance out of town for the weekends really beneficial for everyone involved (especially because Mikaela could not take Bonecrusher with her and at least this way, the poor Pitbull didn't pine too much while she was gone).

Only Pat had been somewhat annoying about her never bringing the guy that she was seeing—like, dating, kind of going steady with but he's not about to marry me or anything crazy around the house, but one single meaningful look from Cal was about enough to shut her up if he noticed that she was starting to get under Mikaela's skin. And Mikaela knew another reason why he didn't want Pat harping on about it, too—this had a lot to do with the conversation she'd had with her dad pretty much exactly a year ago, right after her and Sam had split (when she'd voiced her opinion that she was 'fucking done' with guys).

Cal knew that the break-up had stung her. Cal might not have done very smart things with his life thus far, but he was not a stupid guy, and seeing Mikaela hurt like that had hurt him. This was definitely part of the reason why he'd decided to give Christine to Mikaela with so little persuasion—after all, Christine was a nice ride after they'd fixed her up. And if there was one thing that everybody knew had the power to cheer Mikaela up above all else, it was shiny, badass rides and driving fast.

And so, this was how Mikaela had ended up with a little extra time off during her birthday even before she'd hit the highway, destined for a weekend full of fun with Cal and Pat's blessing. It was just enough time to stop by the liquor store before going home to get her things—'cause what was a twenty-first without a couple of drinks, anyhow? Oh, yeah, she was going to have at least a little to drink, and that was for damn sure.

Mikaela didn't drink a lot, but staying sober on a night like this—when it was her birthday the weather was so fucking gorgeous and the tail-end of the afternoon promised nothing but gorgeous desert wasteland, fast cars, and open highway all the way out of town—would have been a goddamned travesty. So she picked up a bottle of something that looked like she could manage to choke it back if she tried hard enough, and sped home to grab a change of clothes and a shower before she'd dressed up in a cute, short black V-neck dress for the occasion.

The highway was even better than usual. Maybe it was the clear skies, the overwhelming smell of soft asphalt, baking earth, and hot desert sage; or else the daydreams of what was to come that were kickstarting the surges of adrenaline that were making her tingle right down to her toes. She wanted to scream and shout—or it might have just been the sensual rumble of the beloved, supercharged Fury she'd modded in her spare time back in Mike's shop that was making her run just as hot as a V8. Whatever the reason behind her feeling so effing stoked, Mikaela didn't care—all of her razor-sharp intent was focused on driving fast without getting caught, while the clock ticked down the further she got along that ever-more-familiar high-octane freeway that was curved like a goddamned model and led to, well (legally speaking, for confidentiality's sake), the middle of 'utterly nowhere' U.S.A where 'absolutely nothing' existed.

'Absolutely nothing' being one super-hot Autobot leader who was currently expecting her arrival at 'utterly nowhere' (aka NEST base), knowing fully well that it was Mikaela's twenty-first birthday, and who'd been promising a surprise of the likes she had no idea but damn was it probably gonna be good. And this had only made Mikaela's imagination run totally wild, because the kinds of things the two of them did together were not at all as she'd told Cal back at home, nope, no sirrie—chaperones be damned, the young woman was of age! And the way that those seventeen tons of drop-dead gorgeous alien metal made her feel every time they were alone together was a gift from god himself already, so the suggestion of a surprise on top of that had her split somewhere between major catatonia and emergency-grade heat stroke—holy mother of god what is he planning was pretty much all she was capable of thinking right now.

And this just got worse and worse as time went on and on and the roar of Christine's engine faded against the backdrop of the blood-pumping chorus of her favorite AC/DC songs while shadows surrounding the fire-engine-red Plymouth elongated on down the road. Deeper into the wasteland they ventured until evening swallowed them whole and, at length, spat them back out directly in front of NEST gate, Christine with a still-ticking motor and a hood radiating heat waves like an open propane heater and a whole lotta extra-intense sexual tension on Mikaela's part.

God damn, she was about ready to freakin' lose her mind! Newly twenty-one with no plans for the evening except whatever Optimus Prime himself had in store for her—now that was the kind of evening she could get used to!

She'd never been more excited to see NEST's big, hulking chicken-wired gate before, and was nearly ecstatic when it split down the middle so that she could drive inside. She was so excited that, for the first time ever, she did not even object to being poked and prodded with energon sweepers and didn't even complain when she was awarded with an extra frisk on top of them, juuuust because it was her birthday. Once the gatekeepers were satisfied, Mikaela hopped back into Christine, turned the key, (savoring the way the Plymouth fired up with what felt like all of the electric anticipation she herself was feeling) and hit the gas, locking the E-brake to roll a little bit of rubber all down the tarmac just for fun.

Ha, serve the gatesmen right for giving her that extra frisk, she thought. She sure hoped they liked the scent of burnt rubber…

NEST base on Friday nights was usually pretty quiet. Tonight, however, the one thing Mikaela noticed more than anything else as she slowly approached the Autobot's hangar, still excited as all-hell, was how particularly silent the base was. No one was around, not human nor Autobot alike—the airstrip was clear of helicopters and planes and all military-grade vehicles had been stowed away in their respective garages; the windows of the mess hall and rec room were blank and empty and only a few lights could be seen here and there shining from the soldiers' quarters. What the heck?

Mikaela continued to crawl along, looking around in confusion. Where was everybody? And, most importantly, where was Optimus? The Autobot leader was almost always practically waiting for her out on the asphalt outside of his hangar the moment he heard that she was on base, as he had commanded the NEST gate officials to inform him of her arrival.

But this time, he wasn't here. In fact, no one was here.

There hadn't been some kind of problem with the Decepticons, meaning that the Autobots and NEST officials had to suddenly take off somewhere for a battle or something, had there? Last she knew, the 'bots hadn't heard from a 'Con in a good few months, as the terrifying arch-nemeses of the Autobots were currently laying low as per their leader Megatron, presumably—but something about this still didn't feel right.

But just as Mikaela had slowed to a stop dead-center of the asphalt mat, contemplating turning around and going back to the gate to find someone to ask, something finally happened.

A ferocious vehicular roar echoed around the empty tarmac, one that was so rough and wild and just plain loud that there was only one Autobot it could have belonged to. Her heart skipped a beat as the sight of the enormous Peterbilt rounded the corner at the end of the strip at breakneck speed, blowing diesel smoke as his back tires spun out in a perfectly-controlled, ninety-degree drift, aimed straight for her. His clean lines were visible even in the dark, custom flames cut with mirror-glass chrome so smooth you could have sworn that it belonged to a truck straight outta the shop, and he was set for a head-on collision—but it was a game of chicken that she knew she'd win. It was the boss-bot's way of showing off, and sure enough, the asphalt-shaking judder of the semi's jake followed before he came to a stop, the front of his grill nearly touching the end of Christine's nose.

"Damn it, boss," said Mikaela slyly as she cut Christine's engine and stepped smoothly from the car, shutting the door behind her as she approached the enormous and attractive semi-truck. For all the times she'd been around him, all the weekends she'd spent with him in the past year or so, it never got any easier to deal with just how good-looking he was, even in vehicle form. The big semi was chopped, slammed, and loaded just as dangerously as the 'bot's heavy artillery was, and there were just some things about that kind of a rig that couldn't not make any red-blooded human's motor run, in Mikaela's opinion.

"I mean," she continued, clearing her throat pointedly as she tried her absolute best not to stare too much or give away exactly what kinds of thoughts had been crossing the young woman's mind mere moments ago (some of them being particularly fond, ah, memories of afternoons the two of them had shared together lately), "I know it is my birthday and everything, but you don't have to show off that much," she grinned.

Optimus transformed before answering, bending down closer to her level like he usually did, braced with one knee on the ground. He was looking at her straight in the eye with what he clearly wanted to be an innocent expression, but she still caught the slight glimmer of amusement in the corners of his optics. "I can assure you, I was in no way 'showing off', as you have called it," he growled, his slow, level voice making the hairs on the back of her neck stand up this close-to. "I was merely expressing how pleased I am to see you again."

Yup, she thought. He was totally showing off. "Riiiiiight," she teased back sarcastically, blinking a little more than usual because of the intensity of his gaze. "Because it has of course been absolute ages since you last saw me."

"It has felt like it."

Mikaela felt the blood rush to her face automatically. "It hasn't been that long!" she spluttered. "It's only been two weeks!"

"A lot can happen in two earth weeks," he answered, watching her closely as she walked right up to him with her hands on her hips, shaking her head in disbelief while trying her darnedest not to smile. "Have you been well?" he asked her.

But way before she could even begin to think up an answer, Optimus had reached out, and—what the heck, she could not believe what she was seeing, here—the 'bot was holding what was an actual bouquet of roses in-between his forefinger and thumb with all the care in the world as if he was totally worried that he might accidentally squish them at any given moment by accident (which was probably a really justified concern, Mikaela reminded herself), and not only that, but he also had on this really adorable sheepish expression like he was actually kind of shy about it.

"…Oh… ohwow," was all that she could manage.

"I have missed you," said Optimus kindly, looking down at her with total fondness. "I have learned… and not through the world wide web, this time… I have consulted Major Lennox instead… and he has informed me that it is human tradition to gift your romantic interest the flowering earth-plant Rosa Centifola on each anniversary of their birth."

Mikaela's mouth opened and closed, but no sound came out. She had, of course, been given flowers as a gift before by ex-boyfriends—but there was something so wholly different about being given a fricking huge bouquet of gorgeous blood-red roses by Optimus fricking Prime.

She could hardly speak. "Oh my god, Optimus, I-I…" she stuttered, unsure of what to say as she accepted the flowers from the giant robot, who looked completely pleased with himself. "I don't know what to say. Gosh. Wow! …Thank you? They're beautiful."

"And they are not alone in that…" said Optimus, his voice pitched low and heavy as his optics flickered deep cobalt-blue. "You look beautiful as well, Mikaela. And I believe that tonight is of particular significance to you, as it is your twenty-first birth anniversary… I must then congratulate you."

Optimus paused here, looking thoughtful. "Even though, I do find it odd, that humans should wish to celebrate the anniversary of their births, opposed to the dates of their conception. Your conception was twenty-one years and nine earth months ago, was it not?"

Mikaela, who had flushed even deeper at his compliment, laughed at the detail of his response. "Um I have no clue… I suppose so," she giggled, bumping him playfully against the highest part of his knee that she could reach while flashing him her most dazzling smile. "For future reference, a simple 'happy birthday' would have done the trick though, you know, boss… That's how we say it here on earth. And as for why we don't count our, uh, conception date…" Mikaela wrinkled her nose with disgust, "Nobody on this entire planet wants to think about their parents doing that." She shuddered. "Like, ever. Trust me on that one."

Optimus made a thoughtful noise. "…Hm …I suppose you are right."

"Too right," she said, getting down to business as she reopened Christine's door to grab her purse while balancing the gorgeous bouquet of flowers in the crook of her right arm. "Now, I'll admit that I really didn't expect all this wishy-washy mushy stuff from a big strong Autobot leader like you…" she teased, "And not that it isn't fricking adorable—seriously freaking adorable oh my god—but I got all dressed up and drove what, like fifty freaking miles to get out here tonight to see you and celebrate. Hard. …And you have no idea exactly how many party invitations I had to turn down because I'd rather party here with you."

She hesitated for a moment, looking him up-and-down with a smirk—he was so cute, and it was turning her on. Hunched-over like that, she couldn't get a look at how tall he was, but there was still an always-adorkable robo-aesthetic to the way the circular audials on the sides of his head spun as he listened to her (not to mention those eyes, she always felt naked when he looked at her like that, damn—stop undressing me with your optics in public, Optimus Prime. You know the rules, she felt like saying).

Mikaela cleared her throat, forcing herself to concentrate before she continued. "And the little white lies I had to come up with about why it was I couldn't be with any of my actual girlfriends on my twenty-first birthday," she folded her arms, faking looking pissed off. "Do you have any idea how mad they were that I chose to spend tonight with some 'weird ass semi-boyfriend that never even shows his face around town' instead? I'll give you a clue. They're extremely damn livid," she finished, laughing at the way the enormous robot shrunk back, looking sorry.

Semi-boyfriend, she echoed to herself with amusement. She'd had a hard time keeping a straight face when she'd used the pun to her friends.

"I apologize, Mikaela, sincerely, I—"

She silenced him with a single look. "Don't be sorry. Don't forget that I said I'd rather party with you," she grinned, and an expression of relief crossed Optimus's face.

"I understand. Thank you, Mikaela," he said. "And in which case, I am incredibly honoured. I will do everything in my power to make sure that this, ah, most important birth-date of yours is celebrated with enough …enthusiasm to rival some of the best—to use the term you would use—parties—that have ever been thrown by myself or anyone else on the planet of Cybertron."

Mikaela felt her mouth open of its own accord. "Wait, what? You? Threw parties on Cybertron?"

The Autobot leader raised an eyebrow at her. "I was not always this old, Mikaela. I was a young mech, once upon a time, however many eons ago it was. …Not that age has slowed me down, because as you will undoubtedly see before this night is over… it has not. …Although… it has been a very long time since I have tasted high-grade…" he added, almost as an afterthought. "Hm. Nevertheless, I believe that you will find your promised birth-date surprise …overwhelmingly satisfactory."

And as he finished his sentence, the great doors of the Autobot's hangar slid open directly behind him, framing him impressively with blindingly bright white light. It took Mikaela's eyes a moment to adjust, and then another moment before the information of what she was actually seeing caught up with her brain—and then she staggered backwards, overcome and so-totally surprised.