Tried something with a different tone than my previous works. Since my previous fics have been fluffy and light-hearted, this one is a little more serious and angsty. Also, it contains mech/mech spark-sex, so if that's not your thing, no one's makin' ya read this. Also, this contains MAJOR SPOILERS for the IDW comic series All Hail Megatron. Consider yourself warned. ^_^;

This fic is dedicated to the lovely Greenangel for her birthday. X3

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Hearing the commotion off in the distance and the exclamations from those waiting below, he stepped to the edge of the roof. From his vantage point on top of the cracked and abandoned structure which served as their temporary base, the vast and unwelcoming landscape was spread out before him. The once bright and thriving city reduced to a series of gray, broken husks littering the surface of the planet, stretching out to a horizon composed of the jagged silhouettes of crumbling buildings.

The movement and bright paint of the figures in the distance looked completely out of place. Their vibrant and blatant signs of life stood in stark contrast to their hollow and lifeless surroundings, reminding him unpleasantly of the bright glow of spilled energon against a graying corpse. The white and red figure, Drift, effortlessly dispatched one Insecticon scout, but there was another. Drift surely knew it was there, sensed its approach behind him, but he seemed completely unconcerned.

With good reason.

He took the shot. The distance was nothing. The target's extremely close proximity to its intended victim didn't matter. It was an easy shot for him. The Insecticon's carcass dropped and began to blend in with the gray dirt, and he lowered his gun. On the ground below he could hear dull shouts and expressions of surprise as they gazed up at him on the roof. His eyes were still fixed on the figure in the distance. Drift made eye-contact with him across the wide expanse and grinned, then set off again to continue his patrol of the perimeter.

He knew Wheeljack was on the roof behind him even before the other mech spoke. "That- ... that's gotta' be one of the hottest things I've ever seen." He could hear the amorous grin in the inventor's voice and turned to look at him, his expression unreadable, mouth set in a grim line. Something in his face unsettled Wheeljack, and the engineer's light-hearted demeanor faltered. "P-Perceptor?"

"There will be more of them soon. We'll need to leave." He stepped away from the edge of the roof and walked past the inventor toward the stairs. "Come inside. You're vulnerable out in the open."

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Wheeljack remained where he was for a moment, rooted to the spot by concern and confusion over his friend's behavior. He'd known Perceptor for vorns, but he'd never seen him like this.

The physical change didn't surprise him. He'd heard there was an incident. The scientist had sustained near-fatal damage, and had been extensively upgraded while undergoing repairs. It was a relief to know that Perceptor had survived, but the knowledge alone hadn't been enough. He'd desperately wanted to see his friend alive and functioning with his own optics, but they were assigned to different units, light years apart from one another. Meta-cycles had passed since they'd last seen each other, and it had been likely to be much longer than that before they would see each other again, assuming they both survived that long.

When they discovered Kup's unit, stranded just like them on the barren waste that was Cybertron, he hadn't been able to suppress the surge of joy that had rippled through his system. He felt guilty being HAPPY to find that others had been condemned to share their bleak fate, but he couldn't help it. He tried to tell himself that he was happy because, working together, they were more likely to survive and find a way out. In truth, he was just excited by the prospect of seeing his friend.

His spark had fluttered when he first caught sight of Perceptor among Kup's troops. His friend was alive and whole, and he looked GOOD. Of course, Wheeljack had found Perceptor attractive before, but the upgrades served as pleasing accents to the scientist's slight frame. As someone with an appreciation for explosives and weaponry, the inventor also found the sight of Perceptor so heavily armed with two blasters and an impressive looking custom long-range rifle strangely appealing.

They had been close before. Under different circumstances they probably would haven been spark-mates by now. He'd wanted to bond, had even asked Perceptor to bond with him before they'd been assigned to different units and separated. His actions and decisions being governed more by his passions than anything else, Wheeljack tended to live in the moment. It was simultaneously his greatest strength and liability. It made him willing and eager to make the bold leaps into uncharted territory that were necessary for innovation, but it also caused him to be a bit careless and make more mistakes than someone with his level of intelligence should make. In contrast, Perceptor was more level-headed and speculative, preferring to carefully weigh the pros and cons of a situation before choosing his course of action. They complimented one another in that regard, but their extreme personality differences occasionally caused conflicts between them, the spark-bonding issue being one such occasion. Perceptor hadn't accepted his offer. He explained that with the ever present threat of the war, and the fact that the two of them were almost entirely responsible for keeping their faction supplied with the latest weaponry and technology, it would be rationally unwise for them to bond. It would nearly double the risk of being offlined for both of them, since very few ever survived the death of their bond-mates. If they bonded and one of them were killed in battle, it would effectively take them both out and cripple the Autobots' ability to keep up with the Decepticons in terms of technological advancement. As much as it hurt to be turned down, Wheeljack had to concede that Perceptor made a good point. Rationally it would be foolish.

Less than a deca-cycle later, they'd been given their assignments and were on separate ships heading in completely different directions across the galaxy. It was a lucky twist of fate that brought them back together now. Not that either of them really believed in luck or fate, but it WAS quite a coincidence.

Now, as the inventor stood pondering his friend's unfamiliarly cold and withdrawn behavior, he belatedly registered Perceptor's final comment before departing down the stairwell. He nervously shot a glance over his shoulder, almost expecting the dire landscape to be swarming with on-coming insecticons. For once, he was comforted to see nothing but cold gray stretching out to the horizon. They weren't coming yet, but they would be soon, and Perceptor was right. The roof wasn't the safest place to be. He quickly followed after the other mech into the relative safety of their temporary base.

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The upper floor of the temporary base was dark and empty. Most of their group congregated on the lower levels, wanting to stay close to others through some strange mixture of paranoid mistrust and the need for companionship. There was still a traitor in their midst, and the suspicion was causing rifts among their small, battle-worn group. Not being the most social mech to begin with, Perceptor was happy to be spared the tension by adopting the role of silent sentry, keeping watch for the enemy from higher ground where few would come to bother him. But eventually Wheeljack had sought him out, as he'd known the other mech would. He suspected that the only reason it had taken Wheeljack this long to approach him was because the engineer had been too busy assisting Ratchet in the desperate struggle to keep Prime online. Prime was stable now, though, and the rest was up to Ratchet.

His thoughts dwelling on the inventor, he paused in his steps, realizing that his light footfalls were the only sound disturbing the stale silence. Wheeljack hadn't followed him. A flicker of concern crossed his processor and he began to turn back just as the silence was shattered by the inventor's hurried steps clamoring down the stairwell. He tensed at the other mech's apparent haste and his hands twitched toward the the twin blasters holstered neatly in his thighs. "Are they here?"

Wheeljack froze in place. His night-vision having just come online in the darkness to reveal Preceptor tensing in preparation to attack. For a fleeting moment the other mech frightened the inventor. "N-no, I just...thought I'd better stop zoning out and get off the roof." Perceptor relaxed and turned, starting away again. Wheeljack's spark seemed to shrink in on itself slightly. This was the first chance he'd gotten to talk to the scientist since their units had teamed up, and Perceptor would scarcely look at him. Apparently his excitement at seeing his friend again wasn't mutual, but he wasn't ready to give up yet. "Perceptor... Perceptor, will you hold up a minute? I haven't seen you in mega-cycles, can't you just take a second to talk to me?"

"This isn't the time. We have to move." Perceptor kept walking. Wheeljack didn't understand. The enemy could be surrounding them as they spoke, pressing in from all sides to overwhelm them with their vast numbers. They had to keep moving. Every second they hesitated was distance they could be putting between themselves and the swarm.

"Isn't the time? This might be the only time we get! Will you just-... Look, I'm not a moron. I know there's a good chance none of us are gonna' make it through this mess, but it'll be a few breems before we're all set to move again, and I ain't gonna' waste what could be my last few free moments staring at the horizon waiting for those glitches to come for us!" Wheeljack caught the other mech's arm to stop him. "Perc, please..."

Perceptor's steps faltered. Wheeljack had a point, and at the sound of the other mech's plea something broke within him.

Wheeljack felt his friend pause and was about to speak again when he abruptly found himself slammed backward into the rough surface of the wall. His processor reeled with shock, verging on panic as a slender hand grasped his throat. Deadly, skilled fingers brushed over the fuel lines in his neck and he tensed in fear, but they slid past the delicate tubes to trigger a hidden catch near his jaw, retracting his protective mask. Instead of having his fuel lines torn out, warm dermal plating clashed with his own and claimed his mouth in a forceful kiss. His spark surged at the unexpected contact and his fear burned away in a overwhelming rush of lust.

In the past, Wheeljack had always been the more aggressive of the two of them. Perceptor had rarely even initiated an encounter between them, usually content to follow the inventor's lead and submit to his advances. Wheeljack was the more creative one, after all, and enjoyed finding different ways to blow the other mech's circuits, so he'd been perfectly happy to take the lead. The engineer had never really been forceful or rough, though, and Perceptor was always gentle and yielding. There was nothing soft or gentle about THIS Perceptor. Now the slightly-built mech was demanding and borderline violent. Everything about this interaction contrasted incredibly to intimacy they'd shared in past, but Wheeljack had never been adversed to change and new developments, and he faced this one as he did any other. He embraced it head-on.

Perceptor pressed forward, pushing his chest-plate forcefully against the other mech's. Wheeljack winced slightly as his door-wings ground uncomfortably into the wall at his back, but the sensual pull of the scientist's surging spark on his own soon distracted him from his discomfort. Bulky gray arms encircled the other mech, fitting tightly around the slender waist. A dark hand clutched an ear-fin in a vice-like grip, a hot glossa thrust insistently into the inventor's mouth. The soft thrum of cooling systems working to expel excess warmth from rapidly heating systems disturbed the quiet of the upper floor.

As unaccustomed to this role as he was, Wheeljack was surprised at how easy it was to let himself succumb to the other mech's control. Slim hands navigated his frame with expert familiarity, delving into the gaps in his armor to tease the delicate circuitry within while carefully avoiding the most sensitive nodes and wires. He arched pliantly into the other mech's calculated touches, silently begging for deeper, more gratifying contact. It wasn't until a soft, needful keen escaped him that Perceptor finally granted his request.

Sliding his hands to the inventor's back, Perceptor lightly traced his fingertips inward along the edges of the engineer's door-wings until they joined to the other mech's back and he stroked the wing-joints. The other mech's knee-joints gave out beneath him and he moaned the scientist's name, his voice rough with static. Their sparks surged simultaneously, energies reaching out toward one another only to be rebounded back to their sources against still closed chest-plates. Perceptor shuddered with the intensity of it and clamped down firmly on the wing-joints in his hands, stroking them again more forcefully. He brought his mouth close to the inventor's audio receptor to utter a quiet but unquestionable command in his own static-laden rasp. "Open."

Wheeljack complied immediately, fighting off a wave of trepidation as though he were exposing his spark to a stranger rather than a mech with whom he'd freely and enthusiastically spark-shared in the past. His chest-plate split down the center, the panels folded aside, and suddenly they were both bathed in the electric blue light of his spark, which was almost painfully bright in the surrounding darkness.

Perceptor responded in kind, the tempered glass panel on his chest sliding aside along with other internal panels to reveal his own spark. Arcs of electricity leaped from both spark-chambers, the tendrils twining and blending, pulling at each other, sending jolts of pleasure from one mech to the other. Without hesitation, he thrust their chests together, their sparks converging in a pulse of light.

It was surreal. The foreign energy coursing through him from the other mech was so familiar, but it felt completely alien. It felt like Perceptor, but Perceptor didn't feel like THIS. Perceptor slowly burned through his system like a sunrise on an atmosphere-less planet, slowly scorching the surface as it inched over the horizon. He didn't surge in, completely and mercilessly obliterating him from the inside out like a hapless asteroid caught in the wake of an exploding star. And yet this was Perceptor, the energy unmistakable, and that was precisely what he was doing.

The inventor clutched desperately to the mech before him for support as his spark burst within him, the overload wracking his system without warning. His vocalizer shorted out mid-cry as the energy surge swept through him, glitching-out his systems one after another before rebounding on the other mech. Perceptor jerked sharply, limbs spasming slightly at the sheer force of the energy flooding through him and triggering his own overload. His lips parted in a silent scream as the wave of electricity ripped through his systems before dissipating between the two of them, leaving them both shaking, the support of the wall the only thing keeping them upright.

With an effort, Perceptor managed to keep his processor online in the aftermath of their interfacing. Still trembling and unsteady from the excess energy in his system, he disentangled himself from the slightly bulkier mech's grasp and stepped back, leaving the inventor to slide to the floor in a softly quaking heap. Wheeljack's dazed optics slowly brightened as he regained lucidity and he turned a puzzled gaze to the mech now standing over him. The scientist didn't meet his optics. Time and energy were precious, and they'd just wasted a great deal of both. They couldn't afford to wast any more. Turning away, he continued on his course. They should be with the others, helping however they could. Lapses like this were inexcusable.

"Perceptor?..." The voice was heavy with emotion. Hurt, guilt, confusion, and even a soft plea for forgiveness. Wheeljack knew their indulgence could cost them all.

"We don't have much time. You should be helping Ratchet prepare Prime for transportation."

"What about you? It's touch-and-go with Prime. We could really use your help..."

His steps faltered again, but he kept going this time, didn't turn around. "That... isn't what I do anymore..."

Wheeljack remained seated against the wall, even more confused and troubled than he had been to begin with, as he watched the other mech depart down the darkened hallway.

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Somber quiet permeated the new temporary base in the aftermath of their move like settling dust after an explosion. All activity and conversation seemed to be stifled by the dismal mood. The flight from their previous base had been brief and extremely eventful. They'd had a plan, but there had been setbacks, and when they finally managed their short-term escape they were one less in number. Their traitor's identity was uncovered, but by the time the truth had been fully brought to light he was already gone, having thrown his life away to buy them all time. The revelation had been a complete shock. Sunstreaker was one of the few who had never even been implicated. Feelings on the subject of his loss should justifiably have been mixed at best. Sunstreaker was narcissistic, vain, haughty and unfriendly. He'd betrayed them. Unwittingly or not, he was a major player in the the chain of events that had put them in their current predicament. But they'd all fought alongside him at some time or another, his arrogant presence had become a familiar fixture among their ranks, and his final act had gone against his very character. The single most selfless thing he had ever done. With full knowledge that he wouldn't survive, he'd stayed behind to trigger the charge and blow the bridge, to buy them time and try to right his own wrongs. Even those who had never been fond of him felt his loss keenly, and anguish weighed heavily on all of them.

Ratchet was still completely occupied with Prime, so Wheeljack had taken it upon himself to treat the casualties of their move. Aside from the dispiriting loss of Sunstreaker, they had been fortunate to have only one other mech sustain any substantial injury, and it wasn't so serious that the inventor couldn't handle it on his own.

Wheeljack had chosen a small, secluded area to treat his patient, and now he sat against the wall, his patient's head resting across his lap. If asked, he would claim that the position was so that he could keep closer observation over the unconscious mech, but no one bothered to ask. Perceptor had taken some sort of inhibitor dart in the neck and collapsed when they were halfway across the bridge. That had been the hitch in the plan. Perceptor was the linchpin that made the entire plan possible. His specific targeting modification and long-range rifle made him the only mech who could pull off the shot necessary to trigger the explosive charges from the other side of the bridge. Without him the plan couldn't work without a sacrifice.

The dart had been easily removed and Wheeljack didn't have any difficulty repairing the minor damage. Now it was simply a matter of waiting for Perceptor's systems to reboot and come back online, and that was taking longer than usual due to the residual effects of the inhibitor in the dart. In the meantime, the inventor kept watch over the other mech to see that there was no complication to his recovery. As he waited, he contemplated the events of the past few cycles. At first he'd been horrified that the loss they'd suffered could have been prevented if it hadn't been for his tryst with Perceptor shortly before departure. Maybe their departure had been delayed because of their stolen time, or maybe Perceptor had been lagging slightly due to lack of energy and it had resulted in his injury. But he had eventually played the scenario over in his head enough to realize that, rationally, it couldn't have made a discernible difference. Several breems had passed after they'd come down from the roof to join the others before their group was fully prepared and ready to move and, fully energized or otherwise, he doubted that even Blurr would have been able to sense and dodge the oncoming dart. Anyway, the event was over and done, and it couldn't be changed now. Nothing could be gained by pouring over the past and wondering how a different choice could have changed the outcome. Wheeljack lived in the moment. He rarely worried about the future. He never dwelled over the past. At least he never had before.

Looking down at the other mech's unconscious face, the inventor wondered if anything of the friend he'd cherished remained in this mech. He thought fondly of pale blue optics alight with fascination and the joy of discovery, a voice quick with excitement describing brilliant theories and analysis, gentle hands and a patient smile concentrating over mind-bogglingly delicate tasks. This face before him didn't smile, hadn't smiled once since they'd been brought back together. There was no curiosity in these optics, which showed nothing more than cold calculation. This mech never uttered a sound other than what little clipped communication was absolutely necessary, and even the gentle touches from his hands seemed to be laced with scarcely veiled threats. Wheeljack hadn't known it was possible for anyone to change so drastically that he could still miss them when they were literally right in his lap.

Perceptor stirred slightly, and slowly his optics brightened as he came back to consciousness and he gazed, optics cold and blank, at the face peering down at him until it looked away. Slowly sitting up, he lightly touched the newly repaired injury at his neck and ran a quick internal scan to check for damage. Finding none, he finally spoke. "Did we succeed?"

"Well... we made it across the bridge. But we lost Sunstreaker. It turns out he was our traitor all along, but... after you went down... before we even knew what was going on, we were all across the bridge and... he stayed behind. He blew the bridge right before they took him down." Perceptor kept his back to him, but even so the inventor thought he could read the first signs of emotion he'd seen in the other mech since they'd met up again. Indistinctly tensing shoulders, head bowing just slightly. It was subtle, but it was enough. Wheeljack thought he could sense the guilt pressing in on the other mech's spark. Guilt because it was HIS failure, his inability to carry out his part that had cost another's life. He could have been imagining it, but he offered words of comfort anyway, just in case it wasn't his imagination. "It wasn't your fault, Perc. I've already thought it over from every angle. You had to shoot the charges, and you had to be in the open to do it. It put you in a vulnerable position, so there was always a risk you were gonna' be taken down before your final shot... But it coulda' been worse... Primus, when I saw you go down I thought you were a goner... But anyway, it's over now, and... you couldn't have changed what happened."

Perceptor nodded once, said nothing, and stood to leave. Dejectedly, Wheeljack followed suit. He needed to check in with Ratchet and see if he could help any more with Prime, anyway. He was turning to go when he was stopped by a gentle touch on his shoulder. Looking back he saw Perceptor, only half-facing him, not looking directly at him.

"...I missed you, 'Jack..." His voice was soft and genuine, and his features were gentle and kind. A dark, slender hand rested delicately on his shoulder before sliding away with a touch so light it could have been a warm sigh from his vents. For a moment, it was Perceptor. HIS Perceptor.

Then the slender mech turned away and headed for the stairway to the roof to resume his post, the sentry keeping watch from above. Another hardened soldier, not a gentle and brilliant scientist. But at the very least Wheeljack had seen the shadow of his dear friend. Even though the glimpse was fleeting, it was a sign of life. It was enough, and finally he didn't miss Perceptor anymore.

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So there you have it. Hope you enjoyed it. Feedback is appreciated. ^_^