Title: Event Horizon

Continuity: Transformers: Prime, post Season One

Pairings: Ratchet/Sunstreaker, Others to be revealed

Rating: M

Warning: SPOILERS, mechslash, language, possible violence, tactile smut, past spark play/merging

Desc: Ratchet and Sunstreaker are forced to reveal a hidden truth while the Autobots struggle to come to terms with their absent leader.

Disclaimer: I don't own Transformers in any shape or form. I own lots of toys, but that's about it. So these characters are only being borrowed for the sake of our amusement.

A/n: I have only seen the TF: Prime tv series. I've heard that War for Cybertron and Exodus are supposed to be the same continuity. But I've not played/read either of those and only know what there is on Tfwiki. As such, some of the details of the characters backgrounds will differ from what's stated in those continuities.

This fic was supposed to be a cracky oneshot about Knockout's origins. Instead, it turned into a multi-chaptered serious epic. Primus help me. Previous to this, I've only written short flash fics based on Transformers.

I was originally going to use Cybertronian measurements for time, but in the actual show, they use human measurements. So I changed my mind. Except, however, for any possible flashbacks or scenes where the Earth-based Autobots are speaking with new arrivals. Used this chapter: kilovorns (83,000 years)

TL; DR. On to the fic!

Chapter One

"Ratchet!"

The familiar voice pours into the balmy air, along with the sight of a brilliantly crimson mech as he launches himself across open space and throws himself at Ratchet. The medic has seconds to brace himself before he has an armful of Sideswipe, the sound of metal clashing against metal ringing loudly.

An assortment of restrained amusement echoes from the bots of the Earth team, a sound that Ratchet relishes as being rare as of late. So he abides by the humiliation of being tackled with affection by Sideswipe and briefly returns the embrace.

"Didja miss me?" Sideswipe asks as he picks Ratchet up bodily – easy enough as he and his twin have at least four feet on Ratchet – and tries to spin him around.

"Like one misses a case of cosmic rust," Ratchet replies drily and vents loudly as Sideswipe sets him back down on his feet, patting Ratchet on the shoulder.

"Awww." Sideswipe cranes his neck, looking all around them, optics searching the face of each mech behind Ratchet.

Humor fades and Ratchet lowers his vocalizer. "First Aid's not here, Sideswipe. We haven't heard from his team yet."

A smile stretches Sideswipe's mouthplates, but Ratchet has known the twins too long not to recognize a fake response. "It's okay, Ratch. I'm sure he'll show up eventually." He lifts his shoulders in a creak and whine of gears that haven't seen his attending physician in millennia – err, kilovorns. (Ratchet hates that he's become so accustomed to using human time measurements that it has even infected his Cybertronian speech patterns.)

He then passes Ratchet, arms splayed wide in greeting. "Bumblebee!"

A trill of notes and a few beeps are the yellow mech's acknowledgment before Sideswipe bumrushes Bumblebee, too. He lifts the smaller bot further into the air than he did Ratchet, swinging him around and around.

Shaking his head, Ratchet returns his attention to the rather large shuttle that had landed on Earth, at coordinates some distance from their base. They could never be certain the 'Cons (notably, Soundwave) weren't tracking the new arrivals. The shuttle itself has seen better days, blaster marks scoring the hull and the plating riddled with dents.

A golden-yellow mech steps out of the bay, sunlight gleaming off his polished armor, every inch of him the tall and imposing warrior. Ratchet feels his spark whirl in response. It's been millennia since he'd last seen Sunstreaker, and though Ratchet isn't the sort for overly dramatic greetings such as Sideswipe initiated, a part of him is sorely tempted. His fingers ache to touch, his frame feels too small to contain himself, and his spark is leaping and pulsing within his chassis.

Sunstreaker approaches him and stops while only a few feet separate them. His head tilts to the side as his optics leisurely rake Ratchet from head to pede, and something a lot like relief cascades through Ratchet. A tension he didn't know he had seeps out of him and he lifts a hand.

He has to cycle his vocalizer twice to remove the static. "Sunstreaker," Ratchet greets. "Welcome to Earth."

Sunstreaker isn't the sort for overly affectionate greetings either, at least not in public with the optics of their fellow Autobots openly watching their reunion. He takes Ratchet's hand, shaking it modestly. "It's not Cybertron," he says.

"But it's home for now," Ratchet replies, his tone implying far more than his words can manage.

"Ratchet, my mech!"

Reluctantly, Ratchet releases Sunstreaker's hand and shifts to greet the last three mechs as they descend from the Lightyear, their vessel. The sight of Perceptor makes Ratchet grin from ear to ear – at last! Another scientist to help him understand this primitive human technology. Bluestreak just behind is a sight for sore optics, and bringing up the rear is Jazz, hand raised in greeting, a twitch and a rhythm to his motions that is achingly familiar.

It feels a lot like family coming home, though Ratchet would never say such a bathetic thing aloud.

"Jazz," Ratchet greets warmly, hand out in an all-too-human greeting that the shorter mech instantly bypasses in favor of an embrace. Less enthusiastic than Sideswipe's, but equally warm and appreciated.

"Nice planet," the third in command observes, drawing back to look around at the grass beneath them, the tall trees concealing their position from prying human eyes, the bright blue sky and the fluffy white clouds as they trail past. "A mech could get used ta this."

Ratchet watches as Jazz's optics trail over the members of Ratchet's team – everyone since Ratchet had entrusted the humans to bridge them back. They always seemed ridiculously enthused to be granted such an opportunity and Ratchet hadn't planned to be gone any longer than a cycle.

"Where's Prime?"

The silence that sweeps through the concealed clearing reignites the heavy tension. Ratchet can feel the optics boring into the back of his helm. As commander in Prime's absence, Ratchet knows it is up to him to relay the unfortunate truth.

"There's been a... complication," Ratchet says, as delicately as he muster, though he should merely resort to his usual lack of tact. There's no gentle way to tell them what occurred after the battle against Unicron, especially since Ratchet himself had not been there.

"He's with the Decepticons!" Bulkhead blurts out, frame rattling as though he can't contain the truth any longer.

Well... that's one way to put it, Ratchet supposes. It saves him from relying on tact, which his programming has never been good with in the first place.

"What?"

The startled exclamations are in perfect harmony as the new arrivals stare at Ratchet and his team with nothing short of startled confusion and disbelief. Their Prime? Joining the Decepticons? How absurd! They must wonder if Ratchet and his team had lost their processors.

Ratchet sighs – he has picked up far too many mannerisms from the humans. "Come to our base. All of you need energon and I need to look at Bluestreak's knee." He had noticed the gunner trying and failing to hide a limp. "I'll explain everything."

He watches as the new arrivals exchange glances, Jazz's optics narrowing in deep contemplation, no doubt hundreds of thought-patterns coalescing and colliding at once.

Ratchet activates his comm. "Rafael? Bridge us back."

o0o0o

Jazz's arrival means that Ratchet can finally bow out and surrender command to someone with a higher ranking than himself, much to his relief. It isn't so much that he despises being in command, but he can never shake the feeling that it is not his place. He is better suited for the medbay, for the occasional scientific tinkering, and Ratchet always felt he were stepping into the footsteps of a mech much greater than himself. Even if only temporarily.

He spends cycles getting Jazz up to spec on everything. From their first arrival on Earth, their numerous clashes with the Decepticons, the involvement with the humans, and the last ugly battle against Unicron. There is only one secret that Ratchet keeps close to his chassis, and this only because there is someone else who needs to hear it first. As soon as that message is relayed, than Ratchet will gladly pass on the details to his commanding officer.

Ratchet leaves Jazz in the main room, pondering the circumstances and taking the late watch with Bumblebee. The others have settled down in various locations throughout their refitted base, having to double up on rooms since space is a premium. Part of Ratchet is almost giddy. Now that Perceptor is here, he has plans for the science bot to take a stab at that formula for Synthetic Energon. With any luck, they might have a viable, testable sample within days. Perhaps even weeks. One that won't have disastrous consequences like Ratchet's own failed attempt.

He never wishes to make such a mistake again. Optimus had forgiven him his harsh words, but both he and Prime had known they were Ratchet's honest opinion. And Ratchet has yet to forgive himself.

In any case, Ratchet gleefully relinquishes command of the Autobot presence on Earth to Jazz. The new arrivals have spread themselves throughout the base, Jazz and Bumblebee have taken the midnight-hour watch, and Ratchet is now free to procure some recharge of his own, if he so chooses. Except that he doesn't. Because now that there is peace and quiet, Ratchet has only one mech he wishes to seek.

He knows exactly where to look.

Their washracks here on Earth are pitiful compared to what they used to have. Two stalls spewing out cold water with human bedsheets to use as drying cloths. They work in a pinch, but Ratchet has felt on more than one occasion that the humans are only deigning to give the Autobots their scraps and nothing else. Which has not endeared him to Earth's native inhabitants in the slightest.

Of course, Sunstreaker is never one to let a little thing like lack of supplies and adequate facilities stop him from pursuing his favorite past time – washing, oiling, and polishing his plating. It would be the first place he'd go, even before he found out whichever quarters he would share with Sideswipe. Or, as the case may be, whatever berth he might squeeze into with Ratchet.

The sound of falling water is the first to reach Ratchet's audials, and as he approaches the washracks, a quick scan informs him that there is only one mech present within. A perfect opportunity.

The door is partially open, and Ratchet pushes it the rest of the way, pausing in the door frame to admire a view he hasn't been privy to in millennia. Yellow plating gleams under the fluorescent lighting as water trickles over reinforced armor and dips into seams. Sunstreaker has found the soft-clothed brushes brought for the Autobot's use, and Ratchet watches as he carefully applies it to his frame, wiping away all evidence of Earth dust and the grime of being trapped in a small shuttle with other mechs.

Ratchet's spark does that ridiculous pulse and flutter reaction again, as though he's a young bot once more, optics landing upon Sunstreaker for the first time. Though, even then, Ratchet had not been so young.

"I can feel you watching me." Sunstreaker's voice echoes hollowly in the tiny washracks, pinging around the tiled walls and reverberating in Ratchet's audials.

His mouthplates curl up, a chuckle escaping him before he can stop it. "With a view such as this, I cannot help myself."

And the dance begins. The foreplay of words, each carefully chosen, a response cautiously measured and given. Sunstreaker pretending he doesn't give a frag; Ratchet playing that he has better things to do.

In the end, they always find themselves in the same place, sharing a berth and curled together in such a way that no other mech would believe unless they'd seen it with their own optics.

The water shuts off with a creak of rusty, old pipes straining under too much pressure. Sunstreaker swipes one of the cotton sheets from a folded stack nearby and half-turns, the white sheet moving thoroughly over his frame.

"True," Sunstreaker agrees, his optics a gleaming sapphire in the overhanging lights. "There's a real dearth of attractive mech around here."

At his side, Ratchet's fingers twitch, all too willing to take the sheet from Sunstreaker and help his partner finish drying his frame. Yet, there's something in the air, a stink of awkward tension that neither of them are equipped to dispel. Not with their equal lack of consideration.

"... Let me help you with that," Ratchet says. Frag tact. It's never done him any good before, and if being blunt will get him closer to Sunstreaker sooner, than Ratchet is all for it. He's waited millennia to see Sunstreaker again. He's tired of being patient.

He's fragging tired of this whole war, truth be told.

Sunstreaker smirks, but dangles one corner of the sheet in Ratchet's direction. "You just want to put your servos all over me."

"Guilty as charged." Some of the tension lessens as Ratchet strides into the room, putting a bold stride into his movement. He gestures for Sunstreaker to turn around as he takes the cottony sheet and begins to swipe it over the broad swaths of Sunstreaker's dorsal armor.

Their electromagnetic fields come into dizzying contact with their proximity, and Ratchet vents softly as he's once again surrounded by the sensation of Sunstreaker. An altogether familiar and intoxicating feeling. It's like finally coming home, for all that they are trapped on Earth, lightyears away from Cybertron. He can feel Sunstreaker's anxiety and tension and relief and happiness, as sure as Sunstreaker can feel Ratchet's own.

Ratchet carefully sweeps the soft cloth over Sunstreaker's armor, until it gleams beneath his fingers, urging him to touch. The scent of Sunstreaker, all particular oils and melted-metal from his blades and the scent of other, of space where Sunstreaker has been most recently and Ratchet hasn't set foot off this miserable little planet in years... Ratchet's olfactory senses are all but giddy with the newness of it all.

Sunstreaker shifts minutely under his touch, barely noticeable save for the fact Ratchet is paying such close attention. "How long has it been?" he asks quietly.

By the Allspark, it's a length of time that doesn't even bear counting. Ratchet clears static from his vocalizer. "Too many kilovorns," he replies and leans forward, nuzzling against the back of Sunstreaker's shoulder, all that he can reach with their difference in height. Electricity crackles between them.

So... Ratchet's desire is not as one-sided as Sunstreaker might lead him to believe. Cold as space on the outside he may seem. But Ratchet knows the truth, the side that Sunstreaker lets precious few see.

"Does that door lock?"

Ratchet snorts inelegantly. "We hardly having living quarters much less private washracks. And when have you ever cared about being watched?"

Sunstreaker makes a staticky hum. "I was asking for your benefit." He turns around, grabbing Ratchet's hand and pulling it upward so that his mouthplates could nimble on incredibly sensitive fingers. "There's no privacy here."

"Not with Bluestreak in the medbay which, consequently, doubles as my berth," Ratchet mutters sourly, but the words are distracted, his ventilations off rhythm with every press of Sunstreaker's mouth.

"Mmm. We'll make do." His optics darken, oscillating down to narrow bands of sapphire. "What about the humans?"

"Gone home."

"Good." It's practically a purr, the way that single word caresses Ratchet's audial and shivers down his plating.

Sunstreaker releases his hold on Ratchet's hand, but only long enough to grab Ratchet by the shoulders, directing him backward so that he collides with the metallic wall with a dull thunk. The solid hit makes Ratchet's entire frame tremble, but not in an undesirable way. Ratchet groans, heat suffusing his plating, his spark spinning faster out of sheer anticipation.

He lifts his hands, nimble digits dipping into visible seams, caressing sensitive wiring beneath Sunstreaker's plating and dragging a soft ventilation from Sunstreaker. One yellow hand pins Ratchet to the wall, pressing against his shoulder, while the other returns the favor, beginning a hurried exploration of Ratchet's frame. Unexplored territory for Sunstreaker, since this is the first time he's seen Ratchet in his Earth alt-mode.

Sunstreaker himself should be in protoform grey, but as Jazz is sneaky, he has already acquired Earth alt-modes for his entire team. They were, in fact, orbiting Earth for several solar cycles before Ratchet noticed signs of their presence. He suspects that he only realized they were planetside because Jazz allowed him to.

The difference in leadership had never been so obvious until then. Which is just another reason Ratchet is all too willing to surrender command.

Besides, he likes Sunstreaker's choice in alt-mode. Yellow is no surprise, but the sleek lines of the lamborghini call to Ratchet's fingers. He can't help but touch, drag his fingers over the smooth metal, dip into the small crevices, get a light grip on bundles of sensory wires and tug.

Sunstreaker groans static and leans forward, arching into the lightly forceful touch. Their chestplates brush, electricity dancing between their frames, and Ratchet can feel the thrumming of Sunstreaker's spark in that contact. Can feel the heat and energy of it behind the thick armor of Sunstreaker's chestplates. A knee nudges between Ratchet's own, the plating of their legs coming into wonderful, electric contact.

Nimble yellow fingers are quick to stroke over white and red armor, finding the seams that elicit the most vocal response. Ratchet's sensitive neck cables. The conductors in his hips. The cluster of sensors in his chevron...

Ratchet moans, trapped between Sunstreaker and the wall, their energy fields making his engine rumble with need. He digs his fingers into the tiny gaps in Sunstreaker's armor, curling the tips around the edges and pulling Sunstreaker against him. Metal whines as it scrapes – Sunstreaker will bitch about his paint job later – but Ratchet can't be bothered to care. Not right now. Not with Sunstreaker here and close and familiar.

Sapphire optics look down at Ratchet with intense focus, Sunstreaker's mouthplates parting as though his vents aren't enough to expel the heat rising in his circuits.

"Missed you," Sunstreaker says, in Cybertronian no less, his accent faint but still detectable even after all these millenia.

Ratchet shudders, his spark pulsing, chestplates threatening to crack. "... Need you," is all he manages to get out, vocalizer unwilling to respond to his commands. Overload creeps up on him, dancing on the edge of his control.

Sunstreaker's optics flare at him, fingers clenching down on Ratchet's shoulder. "Have me," he growls, always offering, rough tone speaking of his own pending overload.

Any response on Ratchet's part is lost in the roar of his overload, his entire frame trembling as energy races through him, crackling across his plating and making his cooling fans work overtime to compensate for the extra heat. Sunstreaker ventilates sharply and arches against Ratchet, dragged into overload by the electricity crawling over yellow armor, his spark pulsing hot and bright, tangible through the contact in their armor.

Sunstreaker slumps, releasing his grip on Ratchet, but only so that he rest the tip of his helm on Ratchet's shoulder instead. His hands rest gently on the wall to either side of Ratchet to keep his balance, his optics shuttered as his cooling fans click on. Ratchet lifts his hands, lightly stroking yellow plating.

For a long moment, the only sound in the room is that of their fans whirring.

"You don't know how relieved I am that you have made it here," Ratchet says softly, breaking the gentle quiet.

Sunstreaker chuckles. "I can guess. You've no warriors here. Prime's gone. You're surrounded by... fleshies." The distaste in Sunstreaker's tone is a near echo of Ratchet's own original opinion.

"The children aren't so bad," Ratchet replies, words echoing in the otherwise empty washrack. "They can be tolerated. There are other things of greater concern."

Sunstreaker straightens, meeting him optic to optic. "Like Megatron."

"Yes." Ratchet pauses, wondering if it's even possible to phrase what he wants to say tactfully, or if tact will fail him now as it always does. "And..."

"And what, Ratchet?" Sunstreaker asks, their intimacy with each other making it easy for Sunstreaker to read into the medic's hesitation.

Ratchet sighs. "Knockout." What he says is not Knockout however, but the Cybertronian version of said mech's name that should be so familiar to them.

Sunstreaker abruptly stills, drawing back until there is a tangible distance between them, their chestplates no longer touching. "You found him?" Longing vibrates in his tone, longing and no small amount of relief.

Ratchet winces. Finding Knockout is perhaps the only bit of good news. All of the other complications make things not so comforting.

"He's here, Sunstreaker," Ratchet replies. "On Earth. Knockout is here."

a/n: Cliffhangers... yeah, this fics full of them. I wrote most of this during NaNoWriMo. Most of the chapters are done. No beta means I have to do it myself which means, updates will be a bit slower. But I always finish my stories.

New fandoms are hard...

Feedback is welcome and appreciated!