I wondered what the two of them talked about in the barn in so my brain supplied the following. Plot bunnies, brain worms, whatever you call them, I have a problem. I also really like reviews, so please review!

"So this is where you've been hiding... " Megatron remarked haughtily as he lay Optimus on his pallet. "Put out to pasture like an old cow."

Optimus eyed him skeptically, the light tone belying the storm beneath the surface of the other mech's red optics. "That implies that I did not wish to be found. You could have come to me at any point. It is you who has been curiously silent these last few years."

"Ha!" Megatron snorted, "I would have been a fool to come to you. As I recall, when I last offered you a truce, you responded by taking off my head."

Optimus merely rolled his optics, a curiously juvenile reaction. It almost felt like they were young again, young and squabbling in their barracks.

"And you stabbed me in the back." The Prime answered dryly.

Megatron gave a chuckle.

"To very little effect, I'm afraid."

It was Optimus's term to snort. "Please, do not flatter me with false humility."

The two lapsed into silence, eyeing one another for a few moments as Optimus's wheezing exhalations filled the gloom.

"What exactly is wrong with you, anyway?" The grey mech snarled, pretending so hard not to care that he succeeded only in proving the opposite.

"A failing spark," Optimus said cryptically. "As simple as that."

Without a word, the warlord's chest plates slipped open, revealing a pulsing yellow light. His life force. His soul. Megatron met his gaze, his brow ridges lifting, too proud to speak what he was so plainly offering.

Optimus's eyes widened and then softened, processing the intimation. The other mech was offering to merge their sparks, to give Optimus a piece of his life.

"I'm afraid Bumblebee already tried that," Optimus said with sudden gentleness.

"He has only a little spark!" Megatron growled contemptuously. "He doesn't have enough power in his frame to operate a single one of your servos!"

There was a responding sigh.

"I will not stop you if you wish to try, but I am only telling you there is nothing to be done."

Megatron made a snarling noise of frustration, drawing closer to kneel over him, chest plates still open.

Optimus only looked up at him tiredly. The Decepticon was stubborn. He would only accept it if he saw it for himself. After a moment, Optimus closed his optics, and opened up the plating around his core. After a moment, he heard the groan of metal as Megatron leaned over him, pressing their chests together.

For one moment, their two lives crackled as one, casting shadows barely visible behind his closed optics. He felt the weak sputtering of his spark suddenly enlivened by bursts of burning fire, washing over him, thrumming through his servos. It felt warm like the sun on a summer's day, and for a few seconds, it brought relief to his numb extremities.

Megatron was right, his life force was stronger than Bumblebee's, but it was none the more effective. As the warlord withdrew, Optimus felt his pulse slow, the erratic sputtering returning as the fire of the other Cybertronian's life withdrew.

"No...no..." Megatron growled helplessly above him, no doubt watching his blue spark die back down to a flicker. There was the sound of ragged venting and then a snarl of frustration, the thud of a fist slamming into the dirt.

Optimus opened his optics, staring up into a face that no longer bothered to mask its anguish as he closed the chamber around his spark.

"Damn you to the Pit, Optimus." Megatron snarled, grabbing him roughly by the shoulders, and shaking him with pure despairing anger. "Don't do this. You can't do this!"

"We have fought our last fight," Optimus told him. "I am done."

"And who is to be our leader now? That little scraplet in the yard? He was a weakling when I trained him and he is still a weakling now!"

Optimus's optics narrowed, anger flaring inside his processor. "Say another word about Bumblebee," the Prime hissed through his denta, "and, so help me Primus, I will find the strength to kill you, again. That young mech is more worthy to lead than either of us ever was. Despite your best efforts, he survived a slaughter that has all but destroyed our race. A slaughter that you started! He will not repeat our mistakes because he knows the cost of war!"

Megatron fell into a stunned silence, perhaps surprised by the ferocity of Optimus's defense. After a moment, he glanced away, his eyes staring into the darkness, unable to meet the sudden fury in Optimus's words.

"This is not how I wanted it to end." Megatron said at last, his voice strangely placid. "I never thought it would come to...this." There was a chasm in that simple word, a chasm that even its infinitude could not cover.

Optimus leaned back, suddenly overcome with exhaustion. His energetic defense of Bumblebee had taken more than his diminished reserves could sustain.

"I know." Optimus said after a moment. "I know..." His voice trailed off. He was so very tired.

Megatron said nothing. He merely sat there in the darkness with his shoulders slumped, and his face empty and bereft. The Decepticon was thinking. His mind churning with emotions that flashed over his features.

After a few moments, Megatron rose and then knelt, arranging his limbs as he crouched to one knee, bowing his head, his arm crossed over his chest.

"Forgive me, my Prime." The Decepticon said, at last, his voice so quiet it could barely be heard. He was genuflecting, his posture swearing an oath of fealty that he could not bring his vocal processor to utter.

Optimus only laughed weakly. It was all too little too late. "Damn that title." He muttered breathily, closing his optics. "Was that the moment that you came to hate me? Was it the day I claimed that name?"

Megatron did not answer. He remained bowed. Kneeling in obeisance. His silence was answer enough. The Prime left him there for several moments, a part of him bemused, a part of him bereaved. He took no satisfaction in the sight.

"Get off your knees," Optimus commanded softly.

Obediently, Megatron rose.

"I am dying, Megatron. I do not need a subject," Optimus murmured quietly, opening his optics to look up at him. "I need my brother back."

The Decepticon's lips trembled, twitching with unnameable emotion as his gaze drank in Optimus's enfeebled frame. Arrogance, anger, grief, and love, yes, love flared in the red optics.

"Please..." Optimus said, the word uttered so quietly that he barely heard himself say it.

It was that simple word that became Megatron's undoing.

Silently, the warlord crouched low and gathered Optimus into his arms, clutching him with a trembling ferocity that put the Decepticon's grappling to shame.

At last, it seemed Megatron had come to terms with the bitter truth. Within a few hours, Optimus would be gone, and with him would go all that remained of Cybertron. Their war had decimated all the rest.

To live in such a world was not a fate that Optimus envied. His failing spark thrummed with sudden pity for the lonely universe that awaited the failed revolutionary.

"I am so sorry, brother," Optimus murmured into Megatron's chest, tracing the ridges of his armor with a comforting servo. "I am...so very sorry."

The Decepticon's claws scraped along his back, holding him all the more tightly. Optimus could not see his face, but he did not need to in order to know that Megatron was grieving in anticipation of a loss greater than the life of one Cybertronian. He was grieving a dynasty, a wasted lifetime of hatred, a fallen brotherhood, and the last soul that loved him.

His brother had come back to him. And in the end, that miracle was all that really mattered.

In a short while, Optimus would not be here to comfort him. So, for now, Optimus let his weakened servos stroke the armored shoulder, and let his spark weep for the lost soul in his arms.

And that is that. Please review! Thanks!