He could feel the laugh building, a heavy, hot weight in his spark, a whirling maelstrom devouring all else inside him. His spark pulsed in his chest, overfull with it, and it choked his vocalizer, cutting off words.

Somewhere nearby he heard Knock Out's voice, the kind of cruel mockery meant to drown out fear. He heard Starscream snarling, cursing his enemies, vowing revenge. Somewhere in front of him he could see flame, the orange roar matching the burn of the thing filling him. Smoke clogged his intakes, acrid and polluted.

He could think. His reason remained to him, at least. The laughter bubbling up inside him, leaking through the cracks, speeding through his circuitry like some kind of scorching virus, had left him that much.

He could see the devastation around him: the long-dead wasteland of Cybertron, burning anew, the flaming wreckage of the Omega Lock. It was meant to revitalize his world. In a way, it had, searing it anew.

Making it into a new hell.

It's true, then, he thought, fighting against his own frame, desperate to keep the mad laughter contained.

He'd thought he had no mercy left. He'd always been cruel, and centuries of war had only honed that cruelty. It had become his favorite weapon. His constant companion. His comforter in the lonely dark of war, sharp and piercing, awakening him to his duty and his destiny.

He'd had no idea.

It's true, then, Optimus Prime, he marveled, sick to his tanks. You doomed our world - your own home - simply to keep one planet out of my hands.

One worthless world built of debris, collected by the gravity of a sleeping god.

He was glad for the thing he fought within him. It kept him from speaking aloud. No one here would understand his words - except for the very enemy who had doomed his home.

I should have known.

I should have seen this coming.

The Council made you Prime, after all. You went to war with me to keep that title.

You watched Cybertron burn for it. Why should I be surprised that you would set it ablaze again - just to keep Earth from me?

His frame twitched and he doubled over, the laughter bleeding out of him, silent at first and then rising in volume. First he growled, the roars of a wounded beast. Then he opened his mouth, his faceplates twisted in a grimace, his frame shaking as the laughter poured out of him, over and over and over again.

The Council appointed you my greatest enemy, centuries ago. I thought they had made a mistake. I thought they were fools. Idiots beneath my notice, to be swept aside at will once your reason returned to you.

I was the fool.

I did not see that they were right.

They made what they wanted of you and set you loose.

On me. Your leader, your mentor, your guide.

Your enemy.

Because they willed it so.

He could feel the other Decepticons' optics on him. Knock Out, concerned. Starscream, horrified. Soundwave, silently observing as ever he had, but oddly intent, as though even he couldn't understand why Megatron would laugh in the face of such horror.

His spark was a wheel of fire in his chest, set aflame by Prime's atrocity. Looking around him at the blackened sky and the tongues of flame reaching up to lick at it, he knew that the burn searing him from the inside would never leave him.

Whether he remained on Cybertron, returned to Earth, or fled to the cold reaches of space, nothing would soothe him. He would carry this conflagration within him forever, and it would never again be quenched.

There was nothing left for him - for any of them - but revenge. Optimus Prime was nothing to him now, not even a respected and honorable foe. He was a drone, a soulless husk, reformed and reformatted by the Council and given a first and last mission: to stand against Megatron, no matter the cost.

Megatron smiled, a twisted rictus.

Are you proud of your creation, my long-dead enemies?

His little flame whirled in his chest at the thought, pleased, eager to destroy. It warmed him, a horrible warmth. A pure heat, searing away the last vestiges of hope, of respect, of pity.

There was nothing left to do but set the world Optimus had chosen to save ablaze.

Nothing left but to ensure that, in his last moments, the Prime would watch Earth burn. That whatever remained of his old friend's mind be forced to surface again, drawn from the hiding place the Council and the Matrix had fashioned for it. That he perish awake and aware, unable to evade justice at last.

That he see those costs he'd been programmed to pay. That whatever remained of Megatron's old comrade would die, at last, knowing that he'd paid them.

That in his last moment of understanding, he see his adopted world in flames, doomed to the fate he'd forced on Cybertron.

"They can run," Megatron said finally, his own laughter echoing through his mind. He raised a hand, staring at the claws tipping his own fingers, the fires' orange light flickering on their surfaces, pointed and deadly sharp.

He curled his hand into a fist as though grabbing at the flame, catching and holding it, a spark to set a planet ablaze.

"But they can never again run home."